p167

LeetCode p167 Two Sum II - Input array is sorted 题解

1.题目:

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. Please note that your returned answers (both index1 and index2) are not zero-based.
You may assume that each input would have exactly one solution.
Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2

题意:

输入一个数组,和一个目标值。
输出相加得这个目标值的两个下标。

2.解题思路:

从左右两边开始往中间搜索

3.代码


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public class Solution {
public int[] twoSum(int[] numbers, int target) {


int[] ans = new int[2];

int k = numbers.length - 1;
for (int i = 0; i < k;) {
if (numbers[i] + numbers[k] == target) {
return new int[] { i+1, k+1 };
}
if (numbers[i] + numbers[k] < target) {

i++;
continue;
}
if (numbers[i] + numbers[k] > target) {
k--;
continue;
}
}

return ans;
}
}


4.一些总结: