[LeedCode OJ]#217 Contains Duplicate

class Solution
{
public:
    bool containsDuplicate(vector<int>& nums)
    {
        int i,len = nums.size();
        map<int,int> vis;
        for(i = 0; i<len; i++)
        {
            if(vis[nums[i]])
                return true;
            vis[nums[i]] = 1;
        }
        return false;
    }
};