Adds medium two pointer exercise - triples - 3sum

Author: joffilyfe

15.py

@@ -0,0 +1,50 @@
+from typing import List
+import unittest
+
+
+class Solution:
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+        triplets = []
+        nums.sort()
+        size = len(nums)
+
+        for i in range(size - 1):
+            if i > 0 and nums[i] == nums[i - 1]:
+                continue
+
+            j = i + 1
+            z = size - 1
+
+            while j < z:
+                sum = nums[i] + nums[j] + nums[z]
+
+                if sum > 0:
+                    z -= 1
+                elif sum < 0:
+                    j += 1
+                else:
+                    triplets.append([nums[i], nums[j], nums[z]])
+                    j += 1
+                    z -= 1
+
+                    while nums[j] == nums[j - 1] and j < z:
+                        j += 1
+
+        return triplets
+
+
+class Tests(unittest.TestCase):
+    def test_one(self):
+        self.assertEqual(
+            Solution().threeSum(nums=[-1, 0, 1, 2, -1, -4]), [[-1, -1, 2], [-1, 0, 1]]
+        )
+
+    def test_two(self):
+        self.assertEqual(Solution().threeSum(nums=[0, 0, 1]), [])
+
+    def test_three(self):
+        self.assertEqual(Solution().threeSum(nums=[0, 0, 0]), [[0, 0, 0]])
+
+
+if __name__ == "__main__":
+    unittest.main()