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

if(nums.size()<3) return 0;

vector<int> sortedNums;

copy(nums.begin(),nums.end(),back_inserter(sortedNums));

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

int ans,a,sum,diff,mindiff=INT_MAX,indexA,indexB,indexC;

for(int i=0;i<sortedNums.size()-2;i++){

indexA=i;

a=sortedNums[indexA];

if(indexA>0 && a==sortedNums[indexA-1]) continue;

indexB=i+1;

indexC=sortedNums.size()-1;

while(indexB<indexC){

sum=sortedNums[indexA]+sortedNums[indexB]+sortedNums[indexC];

diff=abs(target-sum);

if(diff==0) return sum;

if(diff<mindiff){

mindiff=diff;

ans=sum;

}

if(sum<target) indexB++;

else indexC--;

}

}

return ans;

}