219. There are duplicate elements II
Title description
Given an integer array and an integer k, judge whether there are two different indexes i and j in the array, such that nums [i] = nums [j], and the absolute value of the 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
Problem-solving ideas
-
Search for the current element in the hash table and return true if it is found.
-
Insert the current element in the hash table.
-
If the size of the current hash table exceeds k, delete the oldest element in the hash table.
-
Return false.
Hash table
class Solution {
public boolean containsNearbyDuplicate(int[] nums, int k) {
Set<Integer> set = new HashSet<>();
for (int i = 0; i < nums.length; i++) {
if (set.contains(nums[i]))
return true;
set.add(nums[i]);
if (set.size() > k){
set.remove(nums[i = k]);
}
}
return false;
}
}