DAY3P2.md

Two Sum II - Input Array Is Sorted

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• Question:

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.

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• Example:

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].

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• Solution:

Code :

class Solution {
    public int[] twoSum(int[] arr, int target) {
        int l=0,r=arr.length-1;
        while(arr[l]+arr[r]!=target)
        {
            if(arr[l]+arr[r]>target)
            {
                r--;
            }
            else
                l++;
        }
        return new int[]{l+1,r+1};
    }
}