From a4ebb5a0a1b08111f898ea5518ae5625a6d62f17 Mon Sep 17 00:00:00 2001
From: albinsabu2023 <albinsabu2023@gmail.com>
Date: Fri, 4 Oct 2024 03:16:00 +0530
Subject: [PATCH 1/2] added longestpalindromic substring

---
 C++/LongestPalindromicSubstring.cpp | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 C++/LongestPalindromicSubstring.cpp

diff --git a/C++/LongestPalindromicSubstring.cpp b/C++/LongestPalindromicSubstring.cpp
new file mode 100644
index 0000000..e69de29

From 44e4ba514adde67baa0916e16547b5f4009a6bff Mon Sep 17 00:00:00 2001
From: albinsabu2023 <albinsabu2023@gmail.com>
Date: Fri, 4 Oct 2024 03:20:40 +0530
Subject: [PATCH 2/2] added longestpalindromic substring

---
 C++/LongestPalindromicSubstring.cpp | 71 +++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/C++/LongestPalindromicSubstring.cpp b/C++/LongestPalindromicSubstring.cpp
index e69de29..8cdc79f 100644
--- a/C++/LongestPalindromicSubstring.cpp
+++ b/C++/LongestPalindromicSubstring.cpp
@@ -0,0 +1,71 @@
+#include <iostream>
+#include <string>
+using namespace std;
+/**
+ * @brief
+ * author @albinsabu2023
+ * time complexity O(n*n)
+ * space complexity O(n)
+ *
+ * approach:expand around index
+ * two cases
+ * odd length palindrome (single center index)
+ * even length palindrome (two center index)
+ *
+ */
+class Solution
+{
+public:
+    // Function to expand around the center and find the palindrome
+    string expand(string s, int left, int right)
+    {
+        int n = s.length();
+        while (left >= 0 && right < n && s[left] == s[right])
+        {
+            left--;
+            right++;
+        }
+        return s.substr(left + 1, right - left - 1); // return the palindromic substring
+    }
+
+    // Function to find the longest palindromic substring
+    string longestPalindrome(string s)
+    {
+        if (s.length() == 1)
+            return s; // if the string has only one character, it's the longest palindrome
+        int n = s.length();
+        string ans = ""; // variable to store the longest palindrome
+
+        for (int i = 0; i < n - 1; i++)
+        {
+            // Check for odd-length palindromes (centered at one character)
+            string oddlength = expand(s, i, i);
+            if (oddlength.length() > ans.length())
+            {
+                ans = oddlength;
+            }
+
+            // Check for even-length palindromes (centered between two characters)
+            string evenlength = expand(s, i, i + 1);
+            if (evenlength.length() > ans.length())
+            {
+                ans = evenlength;
+            }
+        }
+
+        return ans;
+    }
+};
+
+int main()
+{
+    Solution sol;
+    string s;
+    cout << "Enter the string: ";
+    cin >> s;
+
+    string result = sol.longestPalindrome(s);
+    cout << "Longest palindromic substring is: " << result << endl;
+
+    return 0;
+}