int threeSumClosest(vector<int> &num, int target) {

int ret=0;

sort(num.begin(), num.end());

bool first = true;

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 (first) {

ret=sum;

first=false;

}

else{

if (abs(sum-target) < abs(ret-target)) {

ret=sum;

}

}

if (ret == target) {

return target;

}

if (sum < target) {

j++;

}

else{

k--;

}

}

}

return ret;

}