【Leetcode】219. Contains Duplicate II（字典操作）

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

题目大意：

给定一个整数数组和一个整数k，找出数组中是否存在两个不同的索引i和j，使得nums [i] = nums [j]并且i和j之间的绝对差值最多为k。

解题思路：

字典即可

class Solution {
public:
    bool containsNearbyDuplicate(vector<int>& nums, int k) {
        unordered_map <int, int> m;
        for(int i=0;i<nums.size();i++){
            if(i>k){
                m.erase(m.find(nums[i-k-1]));
            }
            
            if(m.count(nums[i])){
                return true;
            }
            
            m.insert({nums[i], i});
        }
        return false;
    }
};

class Solution:
    def containsNearbyDuplicate(self, nums: List[int], k: int) -> bool:
        tmp = {}
        for i in range(len(nums)):
            if nums[i] in tmp:
                tmp[nums[i]] += [i]
                if (tmp[nums[i]][len(tmp[nums[i]])-1]-tmp[nums[i]][len(tmp[nums[i]])-2])<=k:
                    return True
            else:
                tmp[nums[i]] = [i]
              
        return False