16

class Solution {
public:
    int threeSumClosest(vector<int>& nums, int target) {
        if(nums.size() < 3) return 0;
        int closest = nums[0]+nums[1]+nums[2];
        sort(nums.begin(), nums.end());
        for(int first = 0 ; first < nums.size()-2 ; ++first) {
            if(first > 0 && nums[first] == nums[first-1]) continue;
            int second = first+1;
            int third = nums.size()-1;
            while(second < third) {
                int curSum = nums[first]+nums[second]+nums[third];
                if(curSum == target) return curSum;
                if(abs(target-curSum)<abs(target-closest)) {
                    closest = curSum;
                }
                if(curSum > target) {
                    --third;
                } else {
                    ++second;
                }
            }
        }
        return closest;
    }
};