[leetcode]219.Contains Duplicate II

题目

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

思路

直接用hashmap即可，以nums[i]为键，以i为值

代码

class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        Map<Integer, Integer> map = new HashMap<>();
        
        for(int i = 0; i < nums.length; i++){
            if(map.containsKey(nums[i]))
                if(i-map.get(nums[i]) <= k) return true;
            map.put(nums[i], i);    
        }
        return false; 
    }
}