优先使用map的find函数而非algorithm里的find函数

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
          vector<int> res;
          for(int i=0;i<nums.size();i++)
          {
                int left = target - nums[i];
                auto dis=find(nums.begin(), nums.end(),left);
                if(dis!= nums.end())
                {
                    if(dis-nums.begin()==i)
                    dis= find(dis+1, nums.end(),left);
                    if(dis!= nums.end())
                    {
                         res.push_back(i);
                         res.push_back(dis-nums.begin());
                         break;
                    }
                }
          }
          return res;        
    }
};

 1 class Solution {
 2 public:
 3     vector<int> twoSum(vector<int>& nums, int target) {
 4           unordered_map<int, int> mapping;
 5           vector<int> result;
 6           for(int i=0; i<nums.size();i++)
 7           {
 8               mapping[nums[i]]= i;
 9           }
10           for(int i=0;i<nums.size();i++)
11           {
12               int gap= target-nums[i];
13               if(mapping.find(gap) !=mapping.end() &&mapping[gap]>i)
14               {
15                   result.push_back(i);
16                   result.push_back(mapping[gap]);
17                   break;
18               }
19           }
20           return result;
21     }
22 };