[LeetCode] 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).

class Solution {
public:
    int threeSumClosest(vector<int> &num, int target) {
        sort(num.begin(), num.end());
        int result = 0x6fffffff;
        for(int i = 0; i < num.size(); i++)
        {
            int j = i+1;
            int k = num.size()-1;
            while(j < k)
            {
                int sum = num[i] + num[j] + num[k];
                if(abs(sum-target) < abs(result-target))
                    result = sum;
                if(result == target)
                    return result;
                if(sum > target)
                    k--;
                else
                    j++;
            }
        }
        return result;
    }
};