219. Contains Duplicate II (Easy)
https://leetcode.com/problems/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
Solutions
class Solution {
public boolean containsNearbyDuplicate(int[] nums, int k) {
if (nums == null || nums.length == 0) {
return false;
}
// Last occurrence of given char
Map<Integer, Integer> lastOcc = new HashMap<>();
for (int i = 0; i < nums.length; i++) {
int val = nums[i];
if (!lastOcc.keySet().contains(val)) {
lastOcc.put(val, i);
continue;
}
// if the distance from last occurrence of this char to current is <= k
if (i - lastOcc.get(val) <= k) {
return true;
}
lastOcc.put(val, i);
}
return false;
}
}