LeetCode219. Contains Duplicate II

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

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思路:这道题的意思是判断数组中重复数字的间隔.只要存在两个相同的数字,且间隔小于k的,就返回True,否则返回False.

所以建立一个字典,保存数字位置.如果遇到了相同数字,比较间隔,小于k则返回True,大于k则更新数字位置.(因为后面再出现重复数字,与更新后数字的位置会更近)直到遍历完数组.

class Solution:
    def containsNearbyDuplicate(self, nums, k):
        """
        :type nums: List[int]
        :type k: int
        :rtype: bool
        """
        dic = {}
        for i,num in enumerate(nums):
            if num in dic:
                if i-dic[num] <= k:
                    return True
            dic[num] = i
        return False