167. Two Sum II - Input array is sorted

Problem Description:

Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2.

Note:

Your returned answers (both index1 and index2) are not zero-based.You may assume that each input would have exactly one solution and you may not use the same element twice.

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.

Analysis:

使用前后两个游标寻找两个元素使他们的和能够等于target值。代码如下：

Code:

class Solution { public int[] twoSum(int[] numbers, int target) { int i = 0, j = numbers.length - 1; while(i < j) { if(target - numbers[j] > numbers[i]) { i++; } else if(target - numbers[j] < numbers[i]) { j--; } else { return new int[]{i + 1, j + 1}; } } return new int[]{-1, -1}; } }