翻译给定一个有n个整数的数组S，找出S中3个数，使其和等于一个给定的数，，target。返回这3个数的和，你可以假定每个输入都有且只有一个结果。例如，给定S = {-1 2 1 -4}，和target = 1。那么最接近target的和是2。(-1 + 2 + 1 = 2)。原文Given an array S of n integers, find given number, target. Return integers. You may assume that each input would have exactly one solution.For example, given array S = {–4}, and target = 1.The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).思考
也许我已经开始体会到上一题中别人写的方法的思想了。
在这个题目中，我们要做以下几件事：
代码class Solution{public:int threeSumClosest(vector<int>& nums, int target) {sort(nums.begin(), nums.end());int len = nums.size();int result = INT_MAX, close = INT_MAX;for (int current = 0; current < len – 2; current++) {int front = current + 1, back = len – 1;while (front < back) {int sum = nums[current] + nums[front] + nums[back];if (sum < target) {if (target – sum < close) {close = target – sum;result = sum;}front++;}else if (sum > target) {if (sum – target < close) {close = sum – target;result = sum;}back–;}else {close = 0;result = target;do {front++;} while (front < back&&nums[front – 1] == nums[front]);do {back–;} while (front < back&&nums[back + 1] == nums[back]);}}while (current < len – 2 && nums[current + 1] == nums[current]) {current++;}}return result;}};
和本道题关联密切的题目推荐：
传送门：LeetCode 15 3Sum（3个数的和） 传送门：LeetCode 18 4Sum（4个数的和）
造物之前，必先造人。
