3Sum Closest leetcode

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).

3sum的变体, 维护一个close记录abs(sum- target)的最小值
如果有sum = target 就返回sum 否则就返回close 排序时间O(nlogn) + 查找O(n^2)=
时间复杂度 O(n^2)

public class Solution {
    public int threeSumClosest(int[] nums, int target) {
        if (nums.length < 3 || nums == null) {
            return Integer.MAX_VALUE;
        }
        int close = Integer.MAX_VALUE - Math.abs(target);//防止溢出
        Arrays.sort(nums);
        for (int i = 0; i < nums.length - 2; i++) {
            int left = i + 1;
            int right = nums.length - 1;
            while (left < right) {
                int sum =nums[i] + nums[left] + nums[right];
                if (sum == target) {
                    return sum;
                } else if (sum < target) {
                    left++;
                } else {
                    right--;
                }
                if (Math.abs(close - target) > Math.abs(sum - target)){
                    close = sum;
                }
            }
        }
        return close;
    }
}