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).

 此题和之前两个three sum的区别在于，此题是求最接近target的值的三个数的和，和之前three sum一样，利用排序，for循环，然后双指针来解决此题，不同之处在于创建一个sum值，每次更新最小三个数组的和。代码如下：

 

public class Solution {

    public int threeSumClosest(int[] nums, int target) {

        Arrays.sort(nums);

        int len = nums.length;

        int sum = nums[0]+nums[1]+nums[2];

        for(int i=0;i<len-2;i++){

            int low = i+1,high = len-1;

            while(low<high){

                int cur = nums[i]+nums[low]+nums[high];

                if(cur<=target){

                    if(Math.abs(sum-target)>Math.abs(cur-target)){

                        sum = cur;

                    }

                    low++;

                }else{

                    if(Math.abs(sum-target)>Math.abs(cur-target)){

                        sum = cur;

                    }

                    high--;

                }

            }

        }

        return sum;

    }

}