probl 2 DSA LAB

#include<stdio.h>

int x[4], N = 4;
int rel[4][4];



int acceptable(int k, int size){
    int j;
    for(int i = 0; i<size; i++)
        for ( j = 0; j < size; j++)
        if (x[j] == k)  //nu exista
                return 0;

        if (rel[k][x[j]] != 1) //prieten cu ultimul din lista
            return 0;

        return 1;// primul si ultimul  om sunt vecini
}

int solution(int k, int i){
    return (i == N - 1 && rel[N - 1][0] == rel[0][N - 1] == 1); //4 elemente
}

void printsolution(){

    for (int i = 0; i < N; i++)
        printf("%d ", x[i]);
}

void back(int i){

    for (int k = 1; k <= N; k++)
    if (acceptable(k, N)){
        x[i] = k;

        if (solution(k, i)){
            printsolution();
            printf("\n");
        }

        else
            back(i + 1);
        x[i] = -1;

    }
}

int main(void){
    rel[0][1] = 1;
    rel[1][0] = 1;
    rel[1][2] = 1;
    rel[2][1] = 1;
    rel[2][3] = 1;
    rel[3][2] = 1;
    rel[3][4] = 1;
    rel[4][3] = 1;
    rel[4][0] = 1;
    rel[0][4] = 1;

    back(0);
    return 0;
}