Create main.cpp

Author: JawadSher

24 - Dynamic Programming Problems/27 - Longest Arithmetic Subsequence of Given Difference/main.cpp

@@ -0,0 +1,28 @@
+class Solution {
+public:
+    // Function to find the length of the longest arithmetic subsequence with the given difference
+    int longestSubsequence(vector<int>& arr, int difference) {
+        int n = arr.size();  // Get the size of the input array
+        unordered_map<int, int> dp;  // Map to store the longest subsequence length for each element
+
+        int ans = 0;  // Variable to store the maximum length of any subsequence found so far
+
+        // Iterate through each element of the array
+        for(int i = 0; i < n; i++) {
+            // Calculate the previous element in the subsequence with the given difference
+            int temp = arr[i] - difference;
+
+            // If there's a subsequence ending with `temp`, we get its length from dp. If not, set prevAns to 0
+            int prevAns = dp.count(temp) ? dp[temp] : 0;
+
+            // Update the longest subsequence ending at arr[i], adding 1 to the length of the previous subsequence
+            dp[arr[i]] = 1 + prevAns;
+
+            // Update the maximum subsequence length found so far
+            ans = max(ans, dp[arr[i]]);
+        }
+
+        // Return the maximum length of the subsequence found
+        return ans;
+    }
+};