added: two sum II

Author: mihirs16

14. Questions/leetcode 167 - two sum II.py

@@ -0,0 +1,21 @@
+# two sum II - input array is sorted | leetcode 167 | https://leetcode.com/problems/two-sum-ii-input-array-is-sorted
+# use two pointers on sorted array; if sum > target slide window left, else slide window right
+
+class Solution:
+    def twoSum(self, numbers: list[int], target: int) -> list[int]:
+        ptrL = 0
+        ptrR = 1
+        N = len(numbers)
+
+        while ptrR < N:
+            s = numbers[ptrR] + numbers[ptrL]
+            if s == target:
+                return [ptrL + 1, ptrR + 1]
+            elif s < target:
+                ptrL += 1
+                ptrR += 1
+            else:
+                ptrL -= 1
+            
+        # unreachable for testcases with exactly one solution
+        return [-1, -1]