Two Sum - Closest to target

Given an array nums of n integers, find two integers in nums such that the sum is closest to a given number, target.

Return the absolute value of difference between the sum of the two integers and the target.

Example

Example1

Input:  nums = [-1, 2, 1, -4] and target = 4
Output: 1
Explanation:
The minimum difference is 1. (4 - (2 + 1) = 1).

Example2

Input:  nums = [-1, -1, -1, -4] and target = 4
Output: 6
Explanation:
The minimum difference is 6. (4 - (- 1 - 1) = 6).

Challenge

Do it in O(nlogn) time complexity.

思路：同向双指针，更新diff即可；

public class Solution {
    /**
     * @param nums: an integer array
     * @param target: An integer
     * @return: the difference between the sum and the target
     */
    public int twoSumClosest(int[] nums, int target) {
        if(nums == null || nums.length == 0) {
            return -1;
        }
        Arrays.sort(nums);
        int i = 0; int j = nums.length - 1;
        int diff = Integer.MAX_VALUE;
        while(i < j) {
            int sum = nums[i] + nums[j];
            if(sum == target) {
                return 0;
            } else if(sum > target) {
                if(sum - target < diff) {
                    diff = sum - target;
                }
                j--;
            } else { // sum < target;
                if(target - sum < diff) {
                    diff = target - sum;
                }
                i++;
            }
        }
        return diff;
    }
}