DataStructure_Algorithm_HandBook_PreForLeetCode

217. Contains Duplicate

Example 1:

Input: nums = [1,2,3,1]
Output: true
```[217. Contains Duplicate](https://leetcode.com/problems/contains-duplicate/)

**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`

**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

Solutions:

题目解析 使用哈希表统计每个元素是否出现过即可。

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