From 0db3ba54c9b6e7e25d0336db7723b61415c527f3 Mon Sep 17 00:00:00 2001
From: julienChemillier <66684524+julienChemillier@users.noreply.github.com>
Date: Sun, 4 Sep 2022 09:22:35 +0200
Subject: [PATCH] Add 5 in language c

---
 c/5-Longest-Palindromic-Substring.c | 42 +++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 c/5-Longest-Palindromic-Substring.c

diff --git a/c/5-Longest-Palindromic-Substring.c b/c/5-Longest-Palindromic-Substring.c
new file mode 100644
index 000000000..884f9dc26
--- /dev/null
+++ b/c/5-Longest-Palindromic-Substring.c
@@ -0,0 +1,42 @@
+
+/*
+Given a string s, return the longest palindromic substring in s.
+Time: O(n^2)
+Space: O(1)
+*/
+
+char* longestPalindrome(char * s){
+    int pos=0;
+    int lenmax=1;
+    for (int i=0; s[i]!='\0'; i++){
+        int g=i, d=i;
+        while (g>=0 && s[d]!='\0' && s[g]==s[d]){        
+            g-=1;
+            d+=1;
+        }
+        d--;
+        g++;
+        if (d-g>=lenmax){
+            lenmax=d-g+1;
+            pos=g;
+        }
+        g=i,d=i+1;
+        while (g>=0 && s[d]!='\0' && s[g]==s[d]){
+            g-=1;
+            d+=1;
+        }
+        d--;
+        g++;
+        
+        if (d-g>=lenmax){
+            lenmax=d-g+1;
+            pos=g;
+        }
+    }
+    char* new_s = (char*)malloc(sizeof(char)*(lenmax+1));
+    new_s[lenmax]='\0';
+    for (int i=0; i<lenmax; i++){
+        new_s[i]=s[i+pos];
+    }
+    return new_s;
+}