16. 3Sum Closest

Posted 2020-10-05

思路：

　　以前做过3sum的题，然后直接使用最朴素的三重循环，感觉方法太笨了，借用大佬的方法；

　　from:http://www.cnblogs.com/grandyang/p/4510984.html

　　先排序，然后卡住一个位置的元素，其他两个坐标处于游离态。

class Solution {
    public int threeSumClosest(int[] nums, int target) {
        Arrays.sort(nums);
        int closest = nums[0] + nums[1] + nums[2];
        int diff = Math.abs(closest - target);
        for(int i = 0; i < nums.length - 2;i++)
        {
            int left = i + 1,right = nums.length - 1;
            while(left < right)
            {
                int newSum = nums[i] + nums[left] + nums[right];
                int newDiff = Math.abs(newSum - target);
                if(newDiff < diff)
                {
                    diff = newDiff;
                    closest = newSum;
                }
                if(newSum < target) left++;
                else                right--;
            }
        }
        return closest;
    }
}