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).

在一组数组中找出 一个三元组(a,b,c)的和,其和最接近target.

和leetcode 15.3Sum题没多大区别,一样的思路.

public class A16_3SumClosest {public int threeSumClosest(int[] nums, int target) {Arrays.sort(nums);int distance = Integer.MAX_VALUE; // 3元组的和与target的距离int ans = nums[0];for(int i = 0; i < nums.length - 2; i++) {int second = i + 1;int third = nums.length - 1;while(second < third) {int sum = nums[i] + nums[second] + nums[third];if(sum == target) {return target;}if (Math.abs(sum - target) < distance) {distance = Math.abs(sum - target);ans = sum;}if(sum > target) {do {third--;} while(second < third && nums[third + 1] == nums[third]);} else {do {second++;} while(second < third && nums[second - 1] == nums[second]);}}while(i < nums.length - 2 && nums[i] == nums[i + 1])i++;}return ans;    }}