Create 01 - Recursive Approach (caused TLE).cpp

Author: JawadSher

24 - Dynamic Programming Problems/37 - Longest Palindromic Subsequence/01 - Recursive Approach (caused TLE).cpp

@@ -0,0 +1,40 @@
+class Solution {
+public:
+    // Recursive helper function to solve the problem
+    // Parameters:
+    // - str: the original string
+    // - revStr: the reversed string
+    // - i: current index in the original string
+    // - j: current index in the reversed string
+    int solve(string str, string revStr, int i, int j) {
+        // Base case: if either index goes out of bounds, return 0
+        if (i >= str.length() || j >= revStr.length()) 
+            return 0;
+        
+        // Initialize the answer variable
+        int ans = 0;
+
+        // If the characters match, add 1 to the result and move to the next indices
+        if (str[i] == revStr[j]) 
+            return 1 + solve(str, revStr, i + 1, j + 1);
+        else {
+            // If the characters do not match, find the maximum result by:
+            // 1. Skipping the current character in the original string
+            // 2. Skipping the current character in the reversed string
+            ans = max(solve(str, revStr, i + 1, j), solve(str, revStr, i, j + 1));
+        }
+
+        // Return the computed answer
+        return ans;
+    }
+
+    // Function to calculate the longest palindromic subsequence
+    int longestPalindromeSubseq(string str) {
+        // Create a reversed version of the input string
+        string revStr = str;
+        reverse(revStr.begin(), revStr.end());
+
+        // Start solving from the first indices of both strings
+        return solve(str, revStr, 0, 0);
+    }
+};