---
title: "219. Contains Duplicate II"
url: "https://laigary.com/interview/coding/219-contains-duplicate-ii"
type: "note"
section: "coding"
date: "2023-01-29"
updated: "2023-01-29"
tags: ["Hash Table"]
---

# 219. Contains Duplicate II

[219\. Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii/)

這一題和 2 Sum 的原理有點像，我們需要用到 Table 來記憶元素出現的位置，不過這個題目只需要記憶著每個字元最後出現的位置即可。

```python
class Solution:
    def containsNearbyDuplicate(self, nums: List[int], k: int) -> bool:
        table = {}

        for i in range(len(nums)):
            num = nums[i]
            if num in table:
                if abs(i - table[num]) <= k:
                    return True
            table[num] = i

        return False

```