add two pointers technique

algorithms/search/two_pointers_technique.py

@@ -0,0 +1,31 @@
+"""
+Two Pointers Technique  algorithm
+Complexity = O(N)
+Returns two pairs that match a specific sum in a sorted array.
+For example, if the array is [1,2,3,4,5] and the sum user searches for is 8.
+The program will return  [3,5], the algorithm works by assigning two pointers(indexes)
+to the array, pointer in the first place and pointer in the last place, and check the
+sum of two elements at the pointer, if the sum of two elements is greater than specific sum
+the last pointer is decremented, if it's smaller the first element is incremented, till we
+find the value we looks for.
+"""
+
+def two_pointers(numbers, value):
+    first_index = 0
+    second_index = len(numbers)-1
+    while first_index < second_index:
+        if numbers[first_index] + numbers[second_index] > value:
+            second_index = second_index-1
+        elif numbers[first_index] + numbers[second_index] < value:
+            first_index = first_index+1
+        else:
+            return [numbers[first_index], numbers[second_index]]
+    return -1
+
+"""
+Test Cases
+"""
+print(two_pointers([1, 2, 3, 4, 5], 8))
+print(two_pointers([1, 7, 9, 10, 20], 27))
+print(two_pointers([1, 7, 9, 10, 20], 34))
+print(two_pointers([10, 7, 9, 10, 20], 20))