LeetCode 136 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).

分析：

跟4sum一样，利用排序的性质尝试所有可能，保证三个数的有序性。

public class Solution {
    public int threeSumClosest(int[] num, int target) {
        int min = Integer.MAX_VALUE;
        int result = 0;
        Arrays.sort(num);
        for(int i=0; i<num.length-2; i++){
            int j=i+1;
            int k=num.length-1;
            while(j<k){
                int sum = num[i]+num[j]+num[k];
                int diff = Math.abs(sum-target);
                if(diff < min){
                    min = diff;
                    result = sum;
                }
                if(sum <= target)
                    j++;
                else
                    k--;
            }
        }
        return result;
    }
}