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>& 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;}};