leetcode(力扣)第十六题：最接近的三数之和_C++

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

由第十五题的官方解法稍加修改而来。依旧使用双指针。双指针真好用。