Longest palindromic substring

Longest Palindromic Substring

Given a string S,find the longest palindromic substring in S.

Sample Input 1    : abaxabaxabb
Sample Output 1  : baxabaxab

Sample Input 2     : babad
Sample Output 2   : bab   (aba also correct)

Sample Input 3   : baad
Sample Output 3 : aa


#include <stdio.h>
#include<string.h>
int main()
{
    char str[50],tmp[50],pal[50];
    int len3=0,len2=0,a=0,len,i,j,k,front,back,count=0;
    gets(str);
    len=strlen(str);
    //palindromic substring of length 3 or more
    for(i=1;i<len;i++)
    {
        front=i+1;
        back=i-1;
        a=0;
        while(back>=0 && front<len)
        {
            if(str[front]==str[back])
            {
                a=0;
                for(k=back;k<=front;k++)
                {
                    tmp[a]=str[k];
                    a++;
                }
                len2=strlen(tmp);
                front++;
                back--;
            }
            else{
                break;
            }
        }
       
        if(len2>len3)
        {
            strcpy(pal,tmp);
            len3=len2;
            count++; // check whether palindromic substring length is 3 or more
        }
    }
    //palindromic substring of length 2
    if(count==0)
    {
        for(i=0;i<len;i++)
        {
            if(str[i]==str[i+1])
            {
                printf("%c%c",str[i],str[i+1]);
                break;
            }
        }
    }
    else
    {
    puts(pal);
    }
    return 0;
}

OUTPUT :

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