Problem

Given an array of integers, find if the array contains any duplicates.

Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.

Example

Input: [1,2,3,1]
Output: true

Input: [1,2,3,4]
Output: false

Input: [1,1,1,3,3,4,3,2,4,2]
Output: true

Code

static int var = [](){
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();
class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        map<int,int> dict;
        for(int i=0;i<nums.size();i++){
            if(dict.find(nums[i])==dict.end())
                dict[nums[i]] = 1;
            else
                return true;
        }
        return false;
    }
};

Result

217. Contains Duplicate.png