3Sum Closest

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).

和3Sum的思路基本一致，但是需要存一个different compare to target 用于进行比较。

public class Solution {
    public int threeSumClosest(int[] num, int target) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(num == null || num.length < 3) return 0;
        Arrays.sort(num);
        int len = num.length;
        int min = Integer.MAX_VALUE;
        for(int i = 0; i < len - 2; i ++){
            int j = i + 1;
            int h = len - 1;
            while(h > j){
                int diff = target - num[i] - num[j] - num[h];
                if(Math.abs(diff) < Math.abs(min)) min = diff;
                if(diff > 0) j ++;
                else if(diff < 0) h --;
                else break;
            }
        }
        return target - min;
    }
}