[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

Diff for: 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
@@ -44,18 +44,21 @@ 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()
         else:
             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)")