Count Number of Pairs With Absolute Difference K LeetCode solution in Java

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class Solution {
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  public int countKDifference(int[] nums, int k) {
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    Map<Integer, Integer> map = new HashMap<>();
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    int res = 0;
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    for (int i = 0; i < nums.length; i++) {
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      if (map.containsKey(nums[i] - k)) {
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        res += map.get(nums[i] - k);
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      }
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      if (map.containsKey(nums[i] + k)) {
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        res += map.get(nums[i] + k);
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      }
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      map.put(nums[i], map.getOrDefault(nums[i], 0) + 1);
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    }
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    return res;
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  }
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}