LeetCode:219. Contains Duplicate II

题目描述

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k.

Example 1:

1 2	Input: nums = [1,2,3,1], k = 3 Output: true

Example 2:

1 2	Input: nums = [1,0,1,1], k = 1 Output: true

Example 3:

1 2	Input: nums = [1,2,3,1,2,3], k = 2 Output: false

这题需要找数组中存在nums[i] == nums[j]，并且i和j的差的绝对值小于等于k。

这里需要用一个字典进行存储，字典的键为nums[i]，值为i。从左到右遍历数组nums，如果nums[i]没有出现在字典的键中，则添加nums[i]到字典里。如果字典中已经有nums[i]，则将比较i与该键所对应的值的差值，如果小于k则返回True，否则更新该值。

代码实现

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class : def containsNearbyDuplicate(self, nums: 'list[int]', k: 'int') -> 'bool': M = {} for i in range(len(nums)): if nums[i] not in M.keys(): M[nums[i]] = i else: if i - M[nums[i]] <= k: return True else: M[nums[i]] = i return False