16. 最接近的三数之和

#include <vector>
#include <algorithm>
#include <iostream>
#include <cmath>
#include <unordered_map>
using namespace std;
class Solution {
public:
    Solution(){}
    ~Solution(){}
    int threeSumClosest(vector<int>& nums, int target) {
        //先对数组进行排序
        sort(nums.begin(),nums.end());
        int len=nums.size();
        int left;
        int right;
        int min=0x7FFFFFFF;
        unordered_map<int,int>map;
        for (int i = 0; i < len; i++)
        {
            //左指针
            left=i+1;
            //右指针
            right=len-1;
            while (left<right)
            {
                int temp=nums[left]+nums[right]+nums[i];
                if(temp==target){
                    return temp;
                }
                //当前和小于target，则左指针加1
                if (temp<target)
                {
                    left=left+1;
                }else{//当前和大于target，则右指针减1
                    right=right-1;
                }
                //绝对值判断是否接近
                if (abs(target-temp)<min)
                {
                    min=abs(target-temp);
                    map.insert(make_pair(min,temp));
                }
            }  
        }
        //用map查出最小绝对值所对应的和
        return map[min]; 
    }
};
 int main(){
    Solution s;
    vector<int> v{0,3,97,102,200};
    cout<<s.threeSumClosest(v,300);
    return 0;
 }