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) {        if(num.size()<3){            return 0;        }                sort(num.begin(),num.end());        int dis=INT_MAX,result=0;        for(int i=0;i<num.size()-2;i++){           int j=i+1,k=num.size()-1,sum=0;           while(j<k){                                sum=num[i]+num[j]+num[k];                if(sum==target){                    return target;                }else if(sum<target){                    j++;                    if(abs(sum-target)<dis){                        dis=abs(sum-target);                        result=sum;                    }                }else{                    k--;                    if(abs(sum-target)<dis){                        dis=abs(sum-target);                        result=sum;                    }                }           }        }        return result;    }};