217.contains-duplicate.cpp

/*
 * @lc app=leetcode id=217 lang=cpp
 *
 * [217] Contains Duplicate
 *
 * https://leetcode.com/problems/contains-duplicate/description/
 *
 * algorithms
 * Easy (60.99%)
 * Likes:    5334
 * Dislikes: 970
 * Total Accepted:    1.7M
 * Total Submissions: 2.9M
 * Testcase Example:  '[1,2,3,1]'
 *
 * 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 <= 10^5
 * -10^9 <= nums[i] <= 10^9
 * 
 * 
 */

// @lc code=start
class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        #include <unordered_set>
        unordered_set <int> uniqnums;
        for (int num:nums){
            //cout<<num;
            if(uniqnums.count(num)>0){
                return true;
            }
            uniqnums.insert(num);
        }
        return false;
    }
};
// @lc code=end