LeetCode217. Contains Duplicate

文章目录

• • 一、题目
  • 二、题解

一、题目

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 <= numsi <= 109

二、题解

class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        unordered_map<int,int> map;
        for(auto x:nums){
            if(map[x] == 1) return true;
            map[x]++;
        }
        return false;
    }
};