K-diff Pairs in an Array LeetCode solution in Java

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// O(n) Time Solution
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class Solution {
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  public int findPairs(int[] nums, int k) {
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    Map<Integer, Integer> map = new HashMap();
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    for (int num : nums) map.put(num, map.getOrDefault(num, 0) + 1);
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    int result = 0;
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    for (int i : map.keySet())
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      if (k > 0 && map.containsKey(i + k) || k == 0 && map.get(i) > 1) result++;
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    return result;
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  }
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}