【leetcode-16】3Sum Closest(java)

问题描述：
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).

分析：该题与leetcode-15及其类似，只是将和为0条件改为了与目标值最小。也即减去目标值的差最接近0.

代码如下：348ms，时间复杂度：O(n2)

public class Solution {    public int threeSumClosest(int[] nums, int target) {        int left,right;        Arrays.sort(nums);//排序        int sum = Integer.MAX_VALUE;        int minusWithTarget = Integer.MAX_VALUE;        int sumWithTriple;        int minus;        for(int i = 0;i<nums.length;i++){            if(i-1>=0&&nums[i]==nums[i-1])                continue;            left = i+1;right = nums.length-1;            while(left<right){                sumWithTriple = nums[i]+nums[left]+nums[right];                minus = sumWithTriple-target;                if(minus==0){                    return sumWithTriple;                }else if(minus>0){                    if(minus<minusWithTarget){                        minusWithTarget = minus;                        sum = sumWithTriple;                    }                    right--;                }else {                    if(-minus<minusWithTarget){                        minusWithTarget = -minus;                        sum=sumWithTriple;                    }                    left++;                }            }        }        return sum;    }}