Palindro

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int duplicavettore(char *, char *, int);
int palindro(char *);
int checkcorr(char *, char *);

int main(int argc, char** argv){
    char ARG1[32], ARG2[32], ARG3[32];
    puts("Inserire tre stringhe");
    scanf("%s%s%s", ARG1, ARG2, ARG3);
    if((checkcorr(ARG1, ARG2)==1) && (palindro(ARG3)==0))
        puts(ARG3);
    else if(palindro(ARG3)==1)
        puts("palindro");
    else
        puts(ARG1);
    return 0;
}

int duplicavettore(char *a, char *b, int n){
    if(n<0)
        return 0;
    for(int i=0;i<n;i++)
        b[i]=a[n-i-1];
    return 1;
}

int palindro(char *s){
    int len=strlen(s);
    int n=len/2;
    char bak[n+1];
    if (duplicavettore(s, bak, n)==0){
        fprintf(stderr, "Duplicazione fallita\n");
        exit(0);
    }
    bak[n]='\0';
    if(strcmp(s+n+len%2, bak)==0)
        return 1;
    return 0;
}

int checkcorr(char * a, char * b){
    char c[strlen(a)+strlen(b)+1];
    sprintf(c, "%s%s", a, b);
    return palindro(c);
}