Longest Arithmetic Subsequence of Given Difference LeetCode solution in Java

1
class Solution {
2
  public int longestSubsequence(int[] arr, int difference) {
3
    // Storing the final answer as 1
4
    int length = arr.length, max_length = 1;
5
    HashMap<Integer, Integer> Terms_till_now = new HashMap<>();
6
    for (int i = 0; i < length; i++) {
7
      /*
8
      Find the number of terms, till curr_element - difference , say terms
9
      Mapping 1 + n to the current term of the sequence, i.e. curr_element
10
      */
11
      int terms =
12
          ((Terms_till_now.get(arr[i] - difference) == null)
13
              ? 0
14
              : Terms_till_now.get(arr[i] - difference));
15
      Terms_till_now.put(arr[i], 1 + terms);
16
      max_length = Math.max(max_length, 1 + terms);
17
    }
18
    return max_length;
19
  }
20
}