From e8e1e3461acfebeaf5aef0ab45faa59b1ae411f0 Mon Sep 17 00:00:00 2001
From: aadarsh patwal <91589322+VIBEXD@users.noreply.github.com>
Date: Fri, 14 Oct 2022 22:23:24 +0530
Subject: [PATCH] solution for longest palindromic subsequence

---
 longest-palindromic-subsequence.cpp | 35 +++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 longest-palindromic-subsequence.cpp

diff --git a/longest-palindromic-subsequence.cpp b/longest-palindromic-subsequence.cpp
new file mode 100644
index 0000000..a8e7b7f
--- /dev/null
+++ b/longest-palindromic-subsequence.cpp
@@ -0,0 +1,35 @@
+class Solution
+{
+public:
+    int check(string &s, int L, int R)
+    {
+        while (L >= 0 and R < s.length() and s[L] == s[R])
+        {
+            L--;
+            R++;
+        }
+        return R - L - 1;
+    }
+
+    string longestPalindrome(string s)
+    {
+
+        int ans = 0, st = 0;
+        int n = s.length();
+
+        for (int i = 0; i < n; i++)
+        {
+            int len1 = check(s, i, i);
+            int len2 = check(s, i, i + 1);
+
+            int len = max(len1, len2);
+
+            if (len > ans)
+            {
+                ans = len;
+                st = i - (len - 1) / 2;
+            }
+        }
+        return s.substr(st, ans);
+    }
+};
\ No newline at end of file