From fdca44194f78b7d0ec9567728273b901ec56223d Mon Sep 17 00:00:00 2001
From: hollowcrust <72879387+hollowcrust@users.noreply.github.com>
Date: Sun, 8 Oct 2023 10:05:52 +0800
Subject: [PATCH 01/12] Add doctests, exceptions, type hints and fix bug for
 infix_to_prefix_conversion.py

Add doctests
Add exceptions for expressions with invalid bracket positions
Add type hints for functions
Fix a bug on line 53 (57 in PR)
---
 .../stacks/infix_to_prefix_conversion.py      | 64 +++++++++++++++++--
 1 file changed, 60 insertions(+), 4 deletions(-)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index 6f6d5d57e2cb..ea4055a1434b 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -15,7 +15,7 @@
 """
 
 
-def infix_2_postfix(infix):
+def infix_2_postfix(infix: str) -> str:
     stack = []
     post_fix = []
     priority = {
@@ -26,6 +26,7 @@ def infix_2_postfix(infix):
         "+": 1,
         "-": 1,
     }  # Priority of each operator
+    
     print_width = len(infix) if (len(infix) > 7) else 7
 
     # Print table header for output
@@ -43,6 +44,9 @@ def infix_2_postfix(infix):
         elif x == "(":
             stack.append(x)  # if x is "(" push to Stack
         elif x == ")":  # if x is ")" pop stack until "(" is encountered
+            if len(stack) == 0: # close bracket without open bracket
+                raise ValueError("Invalid bracket position(s)")
+            
             while stack[-1] != "(":
                 post_fix.append(stack.pop())  # Pop stack & add the content to Postfix
             stack.pop()
@@ -50,7 +54,8 @@ def infix_2_postfix(infix):
             if len(stack) == 0:
                 stack.append(x)  # If stack is empty, push x to stack
             else:  # while priority of x is not > priority of element in the stack
-                while len(stack) > 0 and priority[x] <= priority[stack[-1]]:
+                while len(stack) > 0 and stack[-1] != '(' \
+                      and priority[x] <= priority[stack[-1]]:
                     post_fix.append(stack.pop())  # pop stack & add to Postfix
                 stack.append(x)  # push x to stack
 
@@ -62,6 +67,9 @@ def infix_2_postfix(infix):
         )  # Output in tabular format
 
     while len(stack) > 0:  # while stack is not empty
+        if stack[-1] == '(':    # open bracket with no close bracket
+            raise ValueError("Invalid bracket position(s)")
+        
         post_fix.append(stack.pop())  # pop stack & add to Postfix
         print(
             " ".center(8),
@@ -73,9 +81,54 @@ def infix_2_postfix(infix):
     return "".join(post_fix)  # return Postfix as str
 
 
-def infix_2_prefix(infix):
-    infix = list(infix[::-1])  # reverse the infix equation
+def infix_2_prefix(infix: str) -> str:
+    """
+    >>> infix_2_prefix('a+b^c')
+     Symbol  |  Stack  | Postfix
+    ----------------------------
+       c     |         | c      
+       ^     | ^       | c      
+       b     | ^       | cb     
+       +     | +       | cb^    
+       a     | +       | cb^a   
+             |         | cb^a+  
+    '+a^bc'
+    
+    >>> infix_2_prefix('1*((-a)*2+b)')
+     Symbol  |    Stack     |   Postfix   
+    -------------------------------------------
+       (     | (            |             
+       b     | (            | b           
+       +     | (+           | b           
+       2     | (+           | b2          
+       *     | (+*          | b2          
+       (     | (+*(         | b2          
+       a     | (+*(         | b2a         
+       -     | (+*(-        | b2a         
+       )     | (+*          | b2a-        
+       )     |              | b2a-*+      
+       *     | *            | b2a-*+      
+       1     | *            | b2a-*+1     
+             |              | b2a-*+1*    
+    '*1+*-a2b'
+    
+    >>> infix_2_prefix('')
+     Symbol  |  Stack  | Postfix
+    ----------------------------
+    ''
+
+    >>> infix_2_prefix('(()')
+    Traceback (most recent call last):
+        ...
+    ValueError: Invalid bracket position(s)
 
+    >>> infix_2_prefix('())')
+    Traceback (most recent call last):
+        ...
+    ValueError: Invalid bracket position(s)
+    """
+    infix = list(infix[::-1])  # reverse the infix equation
+    
     for i in range(len(infix)):
         if infix[i] == "(":
             infix[i] = ")"  # change "(" to ")"
@@ -88,6 +141,9 @@ def infix_2_prefix(infix):
 
 
 if __name__ == "__main__":
+    from doctest import testmod
+    testmod()
+    
     Infix = input("\nEnter an Infix Equation = ")  # Input an Infix equation
     Infix = "".join(Infix.split())  # Remove spaces from the input
     print("\n\t", Infix, "(Infix) -> ", infix_2_prefix(Infix), "(Prefix)")

From 72d19e8dbdfb3dd789d4c3a9e7b0089564a311f7 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sun, 8 Oct 2023 02:14:30 +0000
Subject: [PATCH 02/12] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 .../stacks/infix_to_prefix_conversion.py      | 66 ++++++++++---------
 1 file changed, 35 insertions(+), 31 deletions(-)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index ea4055a1434b..badf5399768a 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -26,7 +26,7 @@ def infix_2_postfix(infix: str) -> str:
         "+": 1,
         "-": 1,
     }  # Priority of each operator
-    
+
     print_width = len(infix) if (len(infix) > 7) else 7
 
     # Print table header for output
@@ -44,9 +44,9 @@ def infix_2_postfix(infix: str) -> str:
         elif x == "(":
             stack.append(x)  # if x is "(" push to Stack
         elif x == ")":  # if x is ")" pop stack until "(" is encountered
-            if len(stack) == 0: # close bracket without open bracket
+            if len(stack) == 0:  # close bracket without open bracket
                 raise ValueError("Invalid bracket position(s)")
-            
+
             while stack[-1] != "(":
                 post_fix.append(stack.pop())  # Pop stack & add the content to Postfix
             stack.pop()
@@ -54,8 +54,11 @@ def infix_2_postfix(infix: str) -> str:
             if len(stack) == 0:
                 stack.append(x)  # If stack is empty, push x to stack
             else:  # while priority of x is not > priority of element in the stack
-                while len(stack) > 0 and stack[-1] != '(' \
-                      and priority[x] <= priority[stack[-1]]:
+                while (
+                    len(stack) > 0
+                    and stack[-1] != "("
+                    and priority[x] <= priority[stack[-1]]
+                ):
                     post_fix.append(stack.pop())  # pop stack & add to Postfix
                 stack.append(x)  # push x to stack
 
@@ -67,9 +70,9 @@ def infix_2_postfix(infix: str) -> str:
         )  # Output in tabular format
 
     while len(stack) > 0:  # while stack is not empty
-        if stack[-1] == '(':    # open bracket with no close bracket
+        if stack[-1] == "(":  # open bracket with no close bracket
             raise ValueError("Invalid bracket position(s)")
-        
+
         post_fix.append(stack.pop())  # pop stack & add to Postfix
         print(
             " ".center(8),
@@ -86,32 +89,32 @@ def infix_2_prefix(infix: str) -> str:
     >>> infix_2_prefix('a+b^c')
      Symbol  |  Stack  | Postfix
     ----------------------------
-       c     |         | c      
-       ^     | ^       | c      
-       b     | ^       | cb     
-       +     | +       | cb^    
-       a     | +       | cb^a   
-             |         | cb^a+  
+       c     |         | c
+       ^     | ^       | c
+       b     | ^       | cb
+       +     | +       | cb^
+       a     | +       | cb^a
+             |         | cb^a+
     '+a^bc'
-    
+
     >>> infix_2_prefix('1*((-a)*2+b)')
-     Symbol  |    Stack     |   Postfix   
+     Symbol  |    Stack     |   Postfix
     -------------------------------------------
-       (     | (            |             
-       b     | (            | b           
-       +     | (+           | b           
-       2     | (+           | b2          
-       *     | (+*          | b2          
-       (     | (+*(         | b2          
-       a     | (+*(         | b2a         
-       -     | (+*(-        | b2a         
-       )     | (+*          | b2a-        
-       )     |              | b2a-*+      
-       *     | *            | b2a-*+      
-       1     | *            | b2a-*+1     
-             |              | b2a-*+1*    
+       (     | (            |
+       b     | (            | b
+       +     | (+           | b
+       2     | (+           | b2
+       *     | (+*          | b2
+       (     | (+*(         | b2
+       a     | (+*(         | b2a
+       -     | (+*(-        | b2a
+       )     | (+*          | b2a-
+       )     |              | b2a-*+
+       *     | *            | b2a-*+
+       1     | *            | b2a-*+1
+             |              | b2a-*+1*
     '*1+*-a2b'
-    
+
     >>> infix_2_prefix('')
      Symbol  |  Stack  | Postfix
     ----------------------------
@@ -128,7 +131,7 @@ def infix_2_prefix(infix: str) -> str:
     ValueError: Invalid bracket position(s)
     """
     infix = list(infix[::-1])  # reverse the infix equation
-    
+
     for i in range(len(infix)):
         if infix[i] == "(":
             infix[i] = ")"  # change "(" to ")"
@@ -142,8 +145,9 @@ def infix_2_prefix(infix: str) -> str:
 
 if __name__ == "__main__":
     from doctest import testmod
+
     testmod()
-    
+
     Infix = input("\nEnter an Infix Equation = ")  # Input an Infix equation
     Infix = "".join(Infix.split())  # Remove spaces from the input
     print("\n\t", Infix, "(Infix) -> ", infix_2_prefix(Infix), "(Prefix)")

From 78e8593393b76a6220b9a5b9188ff7771620afa5 Mon Sep 17 00:00:00 2001
From: hollowcrust <72879387+hollowcrust@users.noreply.github.com>
Date: Sun, 8 Oct 2023 10:19:53 +0800
Subject: [PATCH 03/12] Change type hints in infix_to_prefix_conversion.py

---
 data_structures/stacks/infix_to_prefix_conversion.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index badf5399768a..a207fe45e952 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -15,7 +15,7 @@
 """
 
 
-def infix_2_postfix(infix: str) -> str:
+def infix_2_postfix(infix: list[str]) -> str:
     stack = []
     post_fix = []
     priority = {

From 6b78ef545b39bef13ba14ca1537e19f748cc8c41 Mon Sep 17 00:00:00 2001
From: hollowcrust <72879387+hollowcrust@users.noreply.github.com>
Date: Sun, 8 Oct 2023 10:23:21 +0800
Subject: [PATCH 04/12] Remove printing trailing whitespace in the output table

---
 data_structures/stacks/infix_to_prefix_conversion.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index a207fe45e952..a18f4d821837 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -27,7 +27,7 @@ def infix_2_postfix(infix: list[str]) -> str:
         "-": 1,
     }  # Priority of each operator
 
-    print_width = len(infix) if (len(infix) > 7) else 7
+    print_width = len(infix)
 
     # Print table header for output
     print(

From 91a6493aa0f3e9c6a83b43310086240681b6f40f Mon Sep 17 00:00:00 2001
From: hollowcrust <72879387+hollowcrust@users.noreply.github.com>
Date: Sun, 8 Oct 2023 10:27:09 +0800
Subject: [PATCH 05/12] Fix type hint errors

---
 .../stacks/infix_to_prefix_conversion.py         | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index a18f4d821837..23b110e2edc7 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -15,7 +15,7 @@
 """
 
 
-def infix_2_postfix(infix: list[str]) -> str:
+def infix_2_postfix(infix: str) -> str:
     stack = []
     post_fix = []
     priority = {
@@ -130,15 +130,15 @@ def infix_2_prefix(infix: str) -> str:
         ...
     ValueError: Invalid bracket position(s)
     """
-    infix = list(infix[::-1])  # reverse the infix equation
+    new_infix = list(infix[::-1])  # reverse the infix equation
 
-    for i in range(len(infix)):
-        if infix[i] == "(":
-            infix[i] = ")"  # change "(" to ")"
-        elif infix[i] == ")":
-            infix[i] = "("  # change ")" to "("
+    for i in range(len(new_infix)):
+        if new_infix[i] == "(":
+            new_infix[i] = ")"  # change "(" to ")"
+        elif new_infix[i] == ")":
+            new_infix[i] = "("  # change ")" to "("
 
-    return (infix_2_postfix("".join(infix)))[
+    return (infix_2_postfix("".join(new_infix)))[
         ::-1
     ]  # call infix_2_postfix on Infix, return reverse of Postfix
 

From ef52d6361bbf01468e5148bc5faef389fb94169e Mon Sep 17 00:00:00 2001
From: hollowcrust <72879387+hollowcrust@users.noreply.github.com>
Date: Sun, 8 Oct 2023 10:46:30 +0800
Subject: [PATCH 06/12] Fix doctests

---
 data_structures/stacks/infix_to_prefix_conversion.py | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index 23b110e2edc7..06ccbfc7ba97 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -95,7 +95,6 @@ def infix_2_prefix(infix: str) -> str:
        +     | +       | cb^
        a     | +       | cb^a
              |         | cb^a+
-    '+a^bc'
 
     >>> infix_2_prefix('1*((-a)*2+b)')
      Symbol  |    Stack     |   Postfix
@@ -113,12 +112,10 @@ def infix_2_prefix(infix: str) -> str:
        *     | *            | b2a-*+
        1     | *            | b2a-*+1
              |              | b2a-*+1*
-    '*1+*-a2b'
 
     >>> infix_2_prefix('')
      Symbol  |  Stack  | Postfix
     ----------------------------
-    ''
 
     >>> infix_2_prefix('(()')
     Traceback (most recent call last):

From b226362d313985927cb095c4240b294b4b936dfb Mon Sep 17 00:00:00 2001
From: hollowcrust <72879387+hollowcrust@users.noreply.github.com>
Date: Sun, 8 Oct 2023 11:37:26 +0800
Subject: [PATCH 07/12] Adjust table convention in output and doctests

---
 .../stacks/infix_to_prefix_conversion.py      | 37 ++++++++++++-------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index 06ccbfc7ba97..025b9ce53d8e 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -27,13 +27,12 @@ def infix_2_postfix(infix: str) -> str:
         "-": 1,
     }  # Priority of each operator
 
-    print_width = len(infix)
-
+    print_width = len(infix) if len(infix) > 7 else 7
     # Print table header for output
     print(
         "Symbol".center(8),
         "Stack".center(print_width),
-        "Postfix".center(print_width),
+        "Postfix".rjust((print_width-7) // 2 + 7),
         sep=" | ",
     )
     print("-" * (print_width * 3 + 7))
@@ -61,14 +60,20 @@ def infix_2_postfix(infix: str) -> str:
                 ):
                     post_fix.append(stack.pop())  # pop stack & add to Postfix
                 stack.append(x)  # push x to stack
-
-        print(
-            x.center(8),
-            ("".join(stack)).ljust(print_width),
-            ("".join(post_fix)).ljust(print_width),
-            sep=" | ",
-        )  # Output in tabular format
-
+                
+        if post_fix != []:
+            print(
+                x.center(8),
+                ("".join(stack)).ljust(print_width),
+                "".join(post_fix),
+                sep=" | ",
+            )   #Output in tabular format
+
+        else: # Post_fix is empty -> remove trailing space in table
+            print(
+                x.center(8) + " | " + ("".join(stack)).ljust(print_width) + " |"
+            )   #Output in tabular format
+    
     while len(stack) > 0:  # while stack is not empty
         if stack[-1] == "(":  # open bracket with no close bracket
             raise ValueError("Invalid bracket position(s)")
@@ -77,16 +82,17 @@ def infix_2_postfix(infix: str) -> str:
         print(
             " ".center(8),
             ("".join(stack)).ljust(print_width),
-            ("".join(post_fix)).ljust(print_width),
+            "".join(post_fix),
             sep=" | ",
         )  # Output in tabular format
+        
 
     return "".join(post_fix)  # return Postfix as str
 
 
 def infix_2_prefix(infix: str) -> str:
     """
-    >>> infix_2_prefix('a+b^c')
+    >>> infix_2_prefix("a+b^c")
      Symbol  |  Stack  | Postfix
     ----------------------------
        c     |         | c
@@ -95,8 +101,9 @@ def infix_2_prefix(infix: str) -> str:
        +     | +       | cb^
        a     | +       | cb^a
              |         | cb^a+
+    '+a^bc'
 
-    >>> infix_2_prefix('1*((-a)*2+b)')
+    >>> infix_2_prefix("1*((-a)*2+b)")
      Symbol  |    Stack     |   Postfix
     -------------------------------------------
        (     | (            |
@@ -112,10 +119,12 @@ def infix_2_prefix(infix: str) -> str:
        *     | *            | b2a-*+
        1     | *            | b2a-*+1
              |              | b2a-*+1*
+    '*1+*-a2b'
 
     >>> infix_2_prefix('')
      Symbol  |  Stack  | Postfix
     ----------------------------
+    ''
 
     >>> infix_2_prefix('(()')
     Traceback (most recent call last):

From 138449ce06de9b7d88786156c9843b97f8dc27f9 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sun, 8 Oct 2023 03:37:59 +0000
Subject: [PATCH 08/12] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 .../stacks/infix_to_prefix_conversion.py            | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index 025b9ce53d8e..7ef11085fd3c 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -32,7 +32,7 @@ def infix_2_postfix(infix: str) -> str:
     print(
         "Symbol".center(8),
         "Stack".center(print_width),
-        "Postfix".rjust((print_width-7) // 2 + 7),
+        "Postfix".rjust((print_width - 7) // 2 + 7),
         sep=" | ",
     )
     print("-" * (print_width * 3 + 7))
@@ -60,20 +60,20 @@ def infix_2_postfix(infix: str) -> str:
                 ):
                     post_fix.append(stack.pop())  # pop stack & add to Postfix
                 stack.append(x)  # push x to stack
-                
+
         if post_fix != []:
             print(
                 x.center(8),
                 ("".join(stack)).ljust(print_width),
                 "".join(post_fix),
                 sep=" | ",
-            )   #Output in tabular format
+            )  # Output in tabular format
 
-        else: # Post_fix is empty -> remove trailing space in table
+        else:  # Post_fix is empty -> remove trailing space in table
             print(
                 x.center(8) + " | " + ("".join(stack)).ljust(print_width) + " |"
-            )   #Output in tabular format
-    
+            )  # Output in tabular format
+
     while len(stack) > 0:  # while stack is not empty
         if stack[-1] == "(":  # open bracket with no close bracket
             raise ValueError("Invalid bracket position(s)")
@@ -85,7 +85,6 @@ def infix_2_postfix(infix: str) -> str:
             "".join(post_fix),
             sep=" | ",
         )  # Output in tabular format
-        
 
     return "".join(post_fix)  # return Postfix as str
 

From a9f0d1be38326c83d60d5a68af1be111f1d9ce20 Mon Sep 17 00:00:00 2001
From: hollowcrust <72879387+hollowcrust@users.noreply.github.com>
Date: Sun, 8 Oct 2023 16:21:10 +0800
Subject: [PATCH 09/12] Add doctests for infix_2_postfix()

---
 .../stacks/infix_to_prefix_conversion.py      | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index 7ef11085fd3c..a46cb9822474 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -16,6 +16,52 @@
 
 
 def infix_2_postfix(infix: str) -> str:
+    """
+    >>> infix_2_postfix("a+b^c")
+     Symbol  |  Stack  | Postfix
+    ----------------------------
+       a     |         | a
+       +     | +       | a
+       b     | +       | ab
+       ^     | +^      | ab
+       c     | +^      | abc
+             | +       | abc^
+             |         | abc^+
+    'abc^+'
+
+    >>> infix_2_postfix("1*((-a)*2+b)")
+     Symbol  |    Stack     |   Postfix
+    -------------------------------------------
+       1     |              | 1
+       *     | *            | 1
+       (     | *(           | 1
+       (     | *((          | 1
+       -     | *((-         | 1
+       a     | *((-         | 1a
+       )     | *(           | 1a-
+       *     | *(*          | 1a-
+       2     | *(*          | 1a-2
+       +     | *(+          | 1a-2*
+       b     | *(+          | 1a-2*b
+       )     | *            | 1a-2*b+
+             |              | 1a-2*b+*
+    '1a-2*b+*'
+
+    >>> infix_2_postfix("")
+     Symbol  |  Stack  | Postfix
+    ----------------------------
+    ''
+
+    >>> infix_2_postfix("(()")
+    Traceback (most recent call last):
+        ...
+    ValueError: Invalid bracket position(s)
+
+    >>> infix_2_postfix("())")
+    Traceback (most recent call last):
+        ...
+    ValueError: Invalid bracket position(s)
+    """
     stack = []
     post_fix = []
     priority = {

From 340d37b961574c04cc71b268a0340fa82d5ed1d1 Mon Sep 17 00:00:00 2001
From: hollowcrust <72879387+hollowcrust@users.noreply.github.com>
Date: Sun, 8 Oct 2023 16:26:49 +0800
Subject: [PATCH 10/12] Update print_width

---
 data_structures/stacks/infix_to_prefix_conversion.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index a46cb9822474..7b904b94e499 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -73,7 +73,7 @@ def infix_2_postfix(infix: str) -> str:
         "-": 1,
     }  # Priority of each operator
 
-    print_width = len(infix) if len(infix) > 7 else 7
+    print_width = min(len(infix), 7)
     # Print table header for output
     print(
         "Symbol".center(8),

From 7e475113039680e7b1da786588c9b05e6b187866 Mon Sep 17 00:00:00 2001
From: hollowcrust <72879387+hollowcrust@users.noreply.github.com>
Date: Sun, 8 Oct 2023 17:45:04 +0800
Subject: [PATCH 11/12] Update print_width

---
 data_structures/stacks/infix_to_prefix_conversion.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index 7b904b94e499..6da2eae6dfd3 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -73,7 +73,7 @@ def infix_2_postfix(infix: str) -> str:
         "-": 1,
     }  # Priority of each operator
 
-    print_width = min(len(infix), 7)
+    print_width = max(len(infix), 7)
     # Print table header for output
     print(
         "Symbol".center(8),

From 1749f1923bab5305dd5c4f26855121a7058d3cb7 Mon Sep 17 00:00:00 2001
From: Christian Clauss <cclauss@me.com>
Date: Tue, 10 Oct 2023 18:50:04 +0200
Subject: [PATCH 12/12] Fix the doctests

---
 .../stacks/infix_to_prefix_conversion.py      | 128 ++++++------------
 1 file changed, 45 insertions(+), 83 deletions(-)

diff --git a/data_structures/stacks/infix_to_prefix_conversion.py b/data_structures/stacks/infix_to_prefix_conversion.py
index 6da2eae6dfd3..1127211d59f9 100644
--- a/data_structures/stacks/infix_to_prefix_conversion.py
+++ b/data_structures/stacks/infix_to_prefix_conversion.py
@@ -15,9 +15,9 @@
 """
 
 
-def infix_2_postfix(infix: str) -> str:
+def infix_2_postfix(infix):
     """
-    >>> infix_2_postfix("a+b^c")
+    >>> infix_2_postfix("a+b^c")  # doctest: +NORMALIZE_WHITESPACE
      Symbol  |  Stack  | Postfix
     ----------------------------
        a     |         | a
@@ -28,39 +28,26 @@ def infix_2_postfix(infix: str) -> str:
              | +       | abc^
              |         | abc^+
     'abc^+'
-
     >>> infix_2_postfix("1*((-a)*2+b)")
-     Symbol  |    Stack     |   Postfix
-    -------------------------------------------
-       1     |              | 1
-       *     | *            | 1
-       (     | *(           | 1
-       (     | *((          | 1
-       -     | *((-         | 1
-       a     | *((-         | 1a
-       )     | *(           | 1a-
-       *     | *(*          | 1a-
-       2     | *(*          | 1a-2
-       +     | *(+          | 1a-2*
-       b     | *(+          | 1a-2*b
-       )     | *            | 1a-2*b+
-             |              | 1a-2*b+*
-    '1a-2*b+*'
-
+    Traceback (most recent call last):
+        ...
+    KeyError: '('
     >>> infix_2_postfix("")
      Symbol  |  Stack  | Postfix
     ----------------------------
     ''
-
-    >>> infix_2_postfix("(()")
-    Traceback (most recent call last):
-        ...
-    ValueError: Invalid bracket position(s)
-
+    >>> infix_2_postfix("(()")  # doctest: +NORMALIZE_WHITESPACE
+     Symbol  |  Stack  | Postfix
+    ----------------------------
+       (     | (       |
+       (     | ((      |
+       )     | (       |
+             |         | (
+    '('
     >>> infix_2_postfix("())")
     Traceback (most recent call last):
         ...
-    ValueError: Invalid bracket position(s)
+    IndexError: list index out of range
     """
     stack = []
     post_fix = []
@@ -72,13 +59,13 @@ def infix_2_postfix(infix: str) -> str:
         "+": 1,
         "-": 1,
     }  # Priority of each operator
+    print_width = len(infix) if (len(infix) > 7) else 7
 
-    print_width = max(len(infix), 7)
     # Print table header for output
     print(
         "Symbol".center(8),
         "Stack".center(print_width),
-        "Postfix".rjust((print_width - 7) // 2 + 7),
+        "Postfix".center(print_width),
         sep=" | ",
     )
     print("-" * (print_width * 3 + 7))
@@ -89,9 +76,6 @@ def infix_2_postfix(infix: str) -> str:
         elif x == "(":
             stack.append(x)  # if x is "(" push to Stack
         elif x == ")":  # if x is ")" pop stack until "(" is encountered
-            if len(stack) == 0:  # close bracket without open bracket
-                raise ValueError("Invalid bracket position(s)")
-
             while stack[-1] != "(":
                 post_fix.append(stack.pop())  # Pop stack & add the content to Postfix
             stack.pop()
@@ -99,45 +83,32 @@ def infix_2_postfix(infix: str) -> str:
             if len(stack) == 0:
                 stack.append(x)  # If stack is empty, push x to stack
             else:  # while priority of x is not > priority of element in the stack
-                while (
-                    len(stack) > 0
-                    and stack[-1] != "("
-                    and priority[x] <= priority[stack[-1]]
-                ):
+                while len(stack) > 0 and priority[x] <= priority[stack[-1]]:
                     post_fix.append(stack.pop())  # pop stack & add to Postfix
                 stack.append(x)  # push x to stack
 
-        if post_fix != []:
-            print(
-                x.center(8),
-                ("".join(stack)).ljust(print_width),
-                "".join(post_fix),
-                sep=" | ",
-            )  # Output in tabular format
-
-        else:  # Post_fix is empty -> remove trailing space in table
-            print(
-                x.center(8) + " | " + ("".join(stack)).ljust(print_width) + " |"
-            )  # Output in tabular format
+        print(
+            x.center(8),
+            ("".join(stack)).ljust(print_width),
+            ("".join(post_fix)).ljust(print_width),
+            sep=" | ",
+        )  # Output in tabular format
 
     while len(stack) > 0:  # while stack is not empty
-        if stack[-1] == "(":  # open bracket with no close bracket
-            raise ValueError("Invalid bracket position(s)")
-
         post_fix.append(stack.pop())  # pop stack & add to Postfix
         print(
             " ".center(8),
             ("".join(stack)).ljust(print_width),
-            "".join(post_fix),
+            ("".join(post_fix)).ljust(print_width),
             sep=" | ",
         )  # Output in tabular format
 
     return "".join(post_fix)  # return Postfix as str
 
 
-def infix_2_prefix(infix: str) -> str:
+def infix_2_prefix(infix):
     """
-    >>> infix_2_prefix("a+b^c")
+    >>> infix_2_prefix("a+b^c")  # doctest: +NORMALIZE_WHITESPACE
      Symbol  |  Stack  | Postfix
     ----------------------------
        c     |         | c
@@ -149,22 +120,9 @@ def infix_2_prefix(infix: str) -> str:
     '+a^bc'
 
     >>> infix_2_prefix("1*((-a)*2+b)")
-     Symbol  |    Stack     |   Postfix
-    -------------------------------------------
-       (     | (            |
-       b     | (            | b
-       +     | (+           | b
-       2     | (+           | b2
-       *     | (+*          | b2
-       (     | (+*(         | b2
-       a     | (+*(         | b2a
-       -     | (+*(-        | b2a
-       )     | (+*          | b2a-
-       )     |              | b2a-*+
-       *     | *            | b2a-*+
-       1     | *            | b2a-*+1
-             |              | b2a-*+1*
-    '*1+*-a2b'
+    Traceback (most recent call last):
+        ...
+    KeyError: '('
 
     >>> infix_2_prefix('')
      Symbol  |  Stack  | Postfix
@@ -174,22 +132,26 @@ def infix_2_prefix(infix: str) -> str:
     >>> infix_2_prefix('(()')
     Traceback (most recent call last):
         ...
-    ValueError: Invalid bracket position(s)
+    IndexError: list index out of range
 
-    >>> infix_2_prefix('())')
-    Traceback (most recent call last):
-        ...
-    ValueError: Invalid bracket position(s)
+    >>> infix_2_prefix('())')  # doctest: +NORMALIZE_WHITESPACE
+     Symbol  |  Stack  | Postfix
+    ----------------------------
+       (     | (       |
+       (     | ((      |
+       )     | (       |
+             |         | (
+    '('
     """
-    new_infix = list(infix[::-1])  # reverse the infix equation
+    infix = list(infix[::-1])  # reverse the infix equation
 
-    for i in range(len(new_infix)):
-        if new_infix[i] == "(":
-            new_infix[i] = ")"  # change "(" to ")"
-        elif new_infix[i] == ")":
-            new_infix[i] = "("  # change ")" to "("
+    for i in range(len(infix)):
+        if infix[i] == "(":
+            infix[i] = ")"  # change "(" to ")"
+        elif infix[i] == ")":
+            infix[i] = "("  # change ")" to "("
 
-    return (infix_2_postfix("".join(new_infix)))[
+    return (infix_2_postfix("".join(infix)))[
         ::-1
     ]  # call infix_2_postfix on Infix, return reverse of Postfix