【LeetCode】16. 3Sum Closest

题目：

　　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).

思路：和上一题差不多，将三个数的和减去target取绝对值，每次找出误差最小值及对应的三个数的和。

public class Solution {
    public int threeSumClosest(int[] nums, int target) {
        int len=nums.length;
        int closestVal=Integer.MAX_VALUE;
        int closestSum=nums[0]+nums[1]+nums[2];
        Arrays.sort(nums);
        int currentNum=nums[0];
        for(int i=0;i<len-2;i++){
            if(i>0 && nums[i]==currentNum) continue;
            int begin=i+1,end=len-1;
            while(begin<end){
                int sum=nums[i]+nums[begin]+nums[end];
                int absVal=Math.abs(sum-target);
                if(absVal<closestVal){
                    closestVal=absVal;
                    closestSum=sum;
                }else if(sum<target){
                    begin++;
                }else end--;
            }
            currentNum=nums[i];
        }
        return closestSum;
    }
}