[leetcode] 219. Contains Duplicate II @ python

原创于 2019-04-03 11:53:27 发布 · 281 阅读

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本文介绍了一种使用字典存储数值及其索引来判断数组中是否存在两个不同的索引i和j，使得nums[i]=nums[j]且i与j之间的绝对距离不超过k的方法。通过遍历数组并检查当前元素是否已在字典中，若满足条件则返回True。

原题

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:

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

Input: nums = [1,0,1,1], k = 1
Output: true
Example 3:

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

解法

字典存储数值和对应的index, 如果遇到数值已存在且之前的index与现在的index的距离 <= k, 返回True

代码

class Solution(object):
    def containsNearbyDuplicate(self, nums, k):
        """
        :type nums: List[int]
        :type k: int
        :rtype: bool
        """
        d = collections.defaultdict(list)
        for i, n in enumerate(nums):
            if n in d and i - d[n][-1] <= k:
                return True
            else:
                d[n].append(i)
        return False