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
代码
Approach #1 Naive Linear Search
class Solution {
public boolean containsNearbyDuplicate(int[] nums, int k) {
for (int i = 0; i < nums.length; i++) {
for (int j = i + 1; j < Math.min(i + k + 1, nums.length); j++) {
if (nums[i] == nums[j]) return true;
}
}
return false;
}
}
Approach #2 (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;
}
}