TWO-SUM-II

Author: Shikha-code36

Two-pointers/twosumII.py

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+"Leetcode- https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/"
+'''
+Given a 1-indexed array of integers numbers that is already sorted in non-decreasing order, find two numbers such that they add up to a specific target number. Let these two numbers be numbers[index1] and numbers[index2] where 1 <= index1 < index2 <= numbers.length.
+
+Return the indices of the two numbers, index1 and index2, added by one as an integer array [index1, index2] of length 2.
+
+The tests are generated such that there is exactly one solution. You may not use the same element twice.
+
+Your solution must use only constant extra space.
+
+Example 1:
+
+Input: numbers = [2,7,11,15], target = 9
+Output: [1,2]
+Explanation: The sum of 2 and 7 is 9. Therefore, index1 = 1, index2 = 2. We return [1, 2].
+'''
+def twoSum(self, numbers, target):
+    l, r = 0, len(numbers)-1
+    while l < r:
+        sum = numbers[l] + numbers[r]
+        if sum < target:
+            l += 1
+        elif sum > target:
+            r -= 1
+        else:
+            return [l+1, r+1]
+
+#T:O(N)
+#S:O(1)