text: /*
  217. Contains Duplicate
  Easy
  
  Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.
  
   
  
  Example 1:
  
  Input: nums = [1,2,3,1]
  Output: true
  
  Example 2:
  
  Input: nums = [1,2,3,4]
  Output: false
  
  Example 3:
  
  Input: nums = [1,1,1,3,3,4,3,2,4,2]
  Output: true
  
   
  
  Constraints:
  
      1 <= nums.length <= 105
      -109 <= nums[i] <= 109
  
  */
  class Solution {
  public:
      bool containsDuplicate(vector<int>& nums) {
          unordered_map<int,int> m;
          for(int a:nums){
              if(m[a]){
                  return true;
              }
              m[a]=1;
          }
          return false;
      }
  };
  