Added Printing Parentheses cominations problem from CTCI

Author: anubhavshrimal

String_or_Array/ParenthesesCombinations.py

@@ -0,0 +1,30 @@
+"""
+Print all valid (properly opened and closed) combinations of n pairs of parentheses.
+"""
+
+
+def addParentheses(str_arr, leftParenCount, rightParenCount, combinations, index):
+    if leftParenCount < 0 or rightParenCount < 0:
+        return
+    if leftParenCount == 0 and rightParenCount == 0:
+        combinations.append(''.join(str_arr))
+    else:
+        if leftParenCount > 0:
+            str_arr[index] = '('
+            addParentheses(str_arr, leftParenCount - 1, rightParenCount, combinations, index + 1)
+        
+        if rightParenCount > leftParenCount:
+            str_arr[index] = ')'
+            addParentheses(str_arr, leftParenCount, rightParenCount - 1, combinations, index + 1)
+
+
+def generateParentheses(count):
+    str_arr = [''] * (count * 2)
+    combinations = []
+    addParentheses(str_arr, count, count, combinations, 0)
+    return combinations
+
+
+parenthesis_pairs = 3
+combinations = generateParentheses(parenthesis_pairs)
+print(*combinations, sep=', ')