[leetcode] Contains Duplicate

 1 class Solution
 2 {
 3 public:
 4   bool containsDuplicate(vector<int> &nums)
 5   {
 6     set<int> S;
 7     for(int i=0; i<nums.size(); i++)
 8     {
 9       if(S.find(nums[i]) == S.end())
10         S.insert(nums[i]);
11       else
12         return true;
13     }
14     return false;
15   }
16 };

 1 class Solution
 2 {
 3 public:
 4   bool containsDuplicate(vector<int> &nums)
 5   {
 6     sort(nums.begin(), nums.end());
 7     for(int i=1; i<nums.size(); i++)
 8       if(nums[i-1] == nums[i])
 9         return true;
10 
11     return false;
12   }
13 };