Leetcode 16. 3Sum Closest

Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

    For example, given array S = {-1 2 1 -4}, and target = 1.    The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

典型的two pointer

1、遍历一遍数组，注意 i 只能到 len-3 

2、之前要算一遍result

3、然后sort array

public class Solution {    public int threeSumClosest(int[] nums, int target) {        int len = nums.length;        int result = nums[0] + nums[1] + nums[len-1];        Arrays.sort(nums);        for (int i = 0; i < len - 2; i++) {            int start = i + 1;            int end = len - 1;            while (start < end) {                int sum = nums[i] + nums[start] + nums[end];                if (sum > target) end--;                else start++;                if (Math.abs(sum - target) < Math.abs(result - target)) result = sum;            }        }        return result;    }}