16. 3Sum Closest（47.2%）

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).

在一个数组中，找出三个数的和，这个和最接近给出的整数。

import java.util.Arrays;public class Solution {    public int threeSumClosest(int[] nums, int target) {        int len = nums.length;        if (len < 3) {            return 0;        }        // 升序排序        Arrays.sort(nums);        int closestSum = nums[0] + nums[1] + nums[len-1];        if (closestSum == target) {            return target;        }        for (int i = 0, end = len - 3; i <= end; i++) {            int left = i + 1, right = len - 1;            while (left < right) {                int tempSum = nums[i] + nums[left] + nums[right];                // 如果当前和刚好等于target，结束                if (tempSum == target) {                    return target;                } else {                    if (Math.abs(target - closestSum) > Math.abs(target - tempSum)) {                        closestSum = tempSum;                    }                    if (target - tempSum > 0) {                        left++;                    } else {                        right--;                    }                }            }         }        return closestSum;    }}