leetcode 287 Find the Duplicate Number寻找重复数

 1 class Solution {
 2 public:
 3     int findDuplicate(vector<int>& nums) {
 4         unordered_map<int, int> m;
 5         int res;
 6         for(int i=0;i<nums.size();i++){
 7             if(m.count(nums[i])){
 8                 res=nums[i];break;
 9             }
10             m[nums[i]]=i;
11         }
12         return res;
13     }
14 };

 1 class Solution {
 2 public:
 3     int findDuplicate(vector<int>& nums) {
 4         set<int> s;
 5         int res;
 6         for(int i=0;i<nums.size();i++){
 7             if(s.find(nums[i])!=s.end()){
 8                 res=nums[i];break;
 9             }
10             s.insert(nums[i]);
11         }
12         return res;
13     }
14 };