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

int getline(char s[], int lim)
{
    int i;
    char c;
    for (i = 0; i<lim && (c = getchar()) != EOF && c != '\n'; ++i)
        s[i] = c;
    s[i] = '\0';
    while (c != EOF && c != '\n')
        c = getchar();
    return i;
}

int containsChar(char *strng, char c){
    int i;
    int strng_length = strlen(strng);
    for (i = 0; i < strng_length; i++)
    {
        if (strng[i] == c){
            return 1;
        }
    }
    return 0;
}

#define MAX 100
char* removee(char *s, int i, int n){
    int s_length = strlen(s);
    int j;
    char result[MAX + 1];

    strcpy_s(result, MAX, s);
    if (s_length >= i + n){
        for (j = i; j < s_length - n; j++)
        {
            result[j] = result[j + n];
        }
        result[j] = '\0';
        return result;
    }
    else{
        return "";
    }
}

char* getLongestChildrenString(char *s1, char *s2, int current_longest){
    char result[MAX + 1];
    char temp_result[MAX + 1];
    char test[MAX + 1];
    char *in, s1_copy[MAX + 1], s2_copy[MAX + 1];
    int i;

    if (strlen(s1) == 0 || strlen(s2) == 0){
        return "";
    }

    if (current_longest >= strlen(s1) || current_longest >= strlen(s2)){
        return "";
    }

    for (i = 0; i < strlen(s1); i++)
    {
        if (containsChar(s2, s1[i]) == 0){
            strcpy_s(s1, MAX, removee(s1, i, 1));
            i--;
        }
    }
    for (i = 0; i < strlen(s2); i++)
    {
        if (containsChar(s1, s2[i]) == 0)
        {
            strcpy_s(s2, MAX, removee(s2, i, 1));
            i--;
        }
    }
    strcpy_s(result, MAX, "");

    in = strstr(s1, s2);
    if (in){
        return s2;
    }
    in = strstr(s2, s1);
    if (in){
        return s1;
    }

    for (i = 0; i < strlen(s1); i++)
    {
        strcpy_s(test, MAX, removee(s1, i, 1));
        strcpy_s(s2_copy, MAX, s2);
        strcpy_s(temp_result, MAX, getLongestChildrenString(test, s2_copy, current_longest >= strlen(result) ? current_longest : strlen(result)));
        if (strlen(temp_result) > strlen(result))
        {
            strcpy_s(result, MAX, temp_result);
        }
    }

    for (i = 0; i < strlen(s2); i++)
    {
        strcpy_s(test, MAX, removee(s2, i, 1));
        strcpy_s(s1_copy, MAX, s1);
        strcpy_s(temp_result, MAX, getLongestChildrenString(s1_copy, test, current_longest >= strlen(result) ? current_longest : strlen(result)));
        if (strlen(temp_result) > strlen(result)){
            strcpy_s(result, MAX, temp_result);
        }

    }
    return result;

}

int main(int argc, char *argv[]){
    char s1[MAX + 1];
    char s2[MAX + 1];
    char longest_child[MAX + 1];

    printf("Adja meg az elso sztringet: ");
    getline(s1, MAX);
    printf("Adja meg az masodik sztringet: ");
    getline(s2, MAX);

    strcpy_s(longest_child, MAX, getLongestChildrenString(s1, s2, 0));

    if (strcmp(longest_child, "") != 0){
        printf("A leghosszabb gyereksztring: %s\n", longest_child);
    }
    else{
        printf("Nincs a ket szonak kozos gyereksztringje!\n");
    }
}