Added doctest and changing the code to return list in dynamic_programming/subset_generation.py.

dynamic_programming/subset_generation.py

@@ -1,44 +1,50 @@
 # Print all subset combinations of n element in given set of r element.
 
 
-def combination_util(arr, n, r, index, data, i):
+def subset_combinations_dp(elements, n):
     """
-    Current combination is ready to be printed, print it
-    arr[]  ---> Input Array
-    data[] ---> Temporary array to store current combination
-    start & end ---> Staring and Ending indexes in arr[]
-    index  ---> Current index in data[]
-    r ---> Size of a combination to be printed
+    Generate all subset combinations of 'n' elements using dynamic programming.
+
+    Args:
+    elements (list): The input list of elements.
+    n (int): The number of elements in each combination.
+
+    Returns:
+    list: A list of tuples, where each tuple represents a combination.
+
+    Examples:
+    >>> elements = [1, 2, 3, 4]
+    >>> n = 2
+    >>> subset_combinations_dp(elements, n)
+    [(1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4)]
+
+    >>> elements = [1, 2, 3]
+    >>> n = 3
+    >>> subset_combinations_dp(elements, n)
+    [(1, 2, 3)]
+
+    >>> elements = [1, 2, 3]
+    >>> n = 0
+    >>> subset_combinations_dp(elements, n)
+    [()]
     """
-    if index == r:
-        for j in range(r):
-            print(data[j], end=" ")
-        print(" ")
-        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
-    # next (Note that i+1 is passed, but
-    # index is not changed)
-    combination_util(arr, n, r, index, data, i + 1)
-    # The main function that prints all combinations
-    # of size r in arr[] of size n. This function
-    # mainly uses combinationUtil()
-
-
-def print_combination(arr, n, r):
-    # A temporary array to store all combination one by one
-    data = [0] * r
-    # Print all combination using temporary array 'data[]'
-    combination_util(arr, n, r, 0, data, 0)
+    r = len(elements)
+
+    dp = [[] for _ in range(r + 1)]
+
+    dp[0].append([])
+
+    for i in range(1, r + 1):
+        for j in range(i, 0, -1):
+            for prev_combination in dp[j - 1]:
+                dp[j].append(prev_combination + [elements[i - 1]])
+
+    combinations = dp[n]
+
+    return combinations
 
 
 if __name__ == "__main__":
-    # Driver code to check the function above
-    arr = [10, 20, 30, 40, 50]
-    print_combination(arr, len(arr), 3)
-    # This code is contributed by Ambuj sahu
+    import doctest
+
+    doctest.testmod()