[532. K-diff Pairs in an Array] #leetcode

532_0904.java

class Solution {
  // O(n) O(n)
    public int findPairs(int[] nums, int k) {
        if (nums.length < 2 || k < 0) return 0;
        
        HashSet visited = new HashSet();
        HashSet pairs = new HashSet();
        
        for (int n : nums) {
            if (visited.contains(n+k)) {
                pairs.add(n+k < n ? n+k : n);
            }
            if (visited.contains(n-k)) {
                pairs.add(n-k < n ? n-k : n);
            }
            
            visited.add(n);
        }
        
        return pairs.size();
    }
}