Dp subset tests Closes #9943

.gitignore

@@ -86,6 +86,7 @@ celerybeat-schedule
 .venv
 env/
 venv/
+myenv/
 ENV/
 env.bak/
 venv.bak/

dynamic_programming/subset_generation.py

@@ -9,16 +9,32 @@ def combination_util(arr, n, r, index, data, i):
     start & end ---> Staring and Ending indexes in arr[]
     index  ---> Current index in data[]
     r ---> Size of a combination to be printed
+
+    >>> combination_util([1, 2, 3], 3, 2, 0, [0, 0], 0)
+    1 2
+    1 3
+    2 3
+    >>> combination_util([-1,-2,-3], 3, 2, 0, [0, 0], 0)
+    -1 -2
+    -1 -3
+    -2 -3
+
+    >>> combination_util([], 0, 2, 0, [0, 0], 0)
+
+    >>> combination_util([1], 1, 2, 0, [0, 0], 0)
+
+    >>> combination_util([1], 1, 2, 0, [0, 0], 3)
+
+
     """
     if index == r:
-        for j in range(r):
-            print(data[j], end=" ")
-        print(" ")
+        print(" ".join(map(str, data[:r])))
         return
     #  When no more elements are there to put in data[]
     if i >= n:
         return
     # current is included, put next at next location
+
     data[index] = arr[i]
     combination_util(arr, n, r, index + 1, data, i + 1)
     # current is excluded, replace it with
@@ -31,14 +47,51 @@ def combination_util(arr, n, r, index, data, i):
 
 
 def print_combination(arr, n, r):
+    """
+    >>> print_combination([1, 2, 3], 3, 2)
+    1 2
+    1 3
+    2 3
+    >>> print_combination([-1,-2,-3], 3, 2)
+    -1 -2
+    -1 -3
+    -2 -3
+
+    >>> print_combination([], 3, 2)
+
+    >>> print_combination([1], 3, 2)
+
+    >>> print_combination([1, 2, 2], 3, 2)
+    1 2
+    1 2
+    2 2
+
+    >>> print_combination(['a', 'b', 'c'], 3, 2)
+    a b
+    a c
+    b c
+
+    >>> print_combination([1, 'a', 2], 3, 2)
+    1 a
+    1 2
+    a 2
+
+    """
     # A temporary array to store all combination one by one
+    # returns nothing if n < r
+    if len(arr) < r:
+        return
     data = [0] * r
     # Print all combination using temporary array 'data[]'
     combination_util(arr, n, r, 0, data, 0)
 
 
 if __name__ == "__main__":
     # Driver code to check the function above
+    # arr = [10,20,30,40,50]
+    import doctest
+
+    doctest.testmod()
     arr = [10, 20, 30, 40, 50]
     print_combination(arr, len(arr), 3)
     # This code is contributed by Ambuj sahu