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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4. #include <stdbool.h>
  5.  
  6. char* longestPalindrome(char* s) {
  7.     int n = strlen(s) ;
  8.     if(n <= 1)
  9.        return s ;
  10.     int i, j, l ;
  11.     bool table[1000][1000] ;
  12.     for(i = 0 ; i < n ; i++)
  13.        table[i][i] = true ;
  14.     int start = 0, maxLength = 1 ;
  15.  
  16.     for(l = 2 ; l <= n ; l++) {
  17.         for(i = 0 ; i < n-l+1 ; i++) {
  18.             j = i+l-1 ;
  19.             if(l == 2) {
  20.                 if(s[i] == s[j]) {
  21.                     table[i][j] = true ;
  22.                     start = i ;
  23.                     maxLength = 2 ;
  24.                 }
  25.             }
  26.             else {
  27.                 if(table[i+1][j-1] && (s[i] == s[j]) ) {
  28.                     table[i][j] = true ;
  29.                     if(l > maxLength) {
  30.                         start = i ;
  31.                         maxLength = l ;
  32.                     }
  33.                 }
  34.             }
  35.         }
  36.     }
  37.     char *pal = (char *)malloc((maxLength+1) * sizeof(char) ) ;
  38.     for(i = start, j = 0 ; i <= start + maxLength - 1 ; i++, j++)
  39.        pal[j] = s[i] ;
  40.     pal[j] = '\0' ;
  41.     return pal ;
  42. }
  43.  
  44. int main() {
  45.     char str[] = "aaabaaaa" ;
  46.     char *s =  longestPalindrome(str) ;
  47.     printf("%s",s) ;
  48.     return 0 ;
  49. }
Success #stdin #stdout 0s 3036KB
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stdin
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Standard input is empty
stdout
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aaabaaa
https://ideone.com/FqmmNU
language:
C (gcc 8.3)
created:
8 years ago
visibility:
public

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