# [217\. Contains Duplicate](https://leetcode.com/problems/contains-duplicate/)

:::spoiler Solution HashMap

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

- 時間複雜度：$O(n)$
- 空間複雜度：$O(n)$
:::