16.最接近的三数之和

方法：排序+双指针

class Solution {
    public int threeSumClosest(int[] nums, int target) {
        Arrays.sort(nums);
        int ans = nums[0] + nums[1] + nums[2];
        for(int i = 0;i<nums.length;i++){
            int start = i+1,end = nums.length - 1;
            while(start < end){
                int sum = nums[start] + nums[end] + nums[i];
                if(Math.abs(target - sum) < Math.abs(target - ans)){
                    ans = sum;
                }
                if(sum > target){
                    end--;
                }else if(sum < target){
                    start++;
                }else{
                    return ans;
                }
            }
        }
        return ans;
    }
}