bfs path reconstruct

#include<iostream>
#include<time.h>
#include<stdlib.h>
#include<vector>

using namespace std;

int E[10][10];
int visited[10];
vector<int> parent;

struct queue{
	vector <int> arr;
	int front;
	int size;
	void enqueue(queue &a, int b){
	a.arr.push_back(b);
	a.size++;
	}
	int dequeue(queue &a){
	int x = a.arr[a.front];
	a.front++;
	a.size--;
	return x;
	}
};

void bfs(int i){
    for(int j = 1; j < 10; j++){
        visited[j] = 0;
        parent.push_back(-1);
    }
    queue Q;
    Q.front = 0;
    Q.size = 0;
    visited[i] = 1;
    Q.enqueue(Q, i);

    while(Q.size != 0){
        int a = Q.dequeue(Q);
        for(int k = 1; k < 10; k++) {
            if(E[a][k] == 1){
                if(visited[k] == 0){
                    visited[k] = 1;
                    parent[k] = a;
                    Q.enqueue(Q, k);
                }
            }
        }
    }
}

int main() {
    E[1][2] = 1;
    E[2][1] = 1;
    E[3][1] = 1;
    E[1][3] = 1;
    E[2][4] = 1;
    E[4][2] = 1;
    E[9][8] = 1;
    E[8][9] = 1;
    E[7][6] = 1;
    E[6][7] = 1;
    E[6][3] = 1;
    E[3][6] = 1;
    E[4][6] = 1;
    E[6][4] = 1;
    E[4][5] = 1;
    E[5][4] = 1;
    E[4][8] = 1;
    E[8][4] = 1;
    bfs(1);
    cout << "Reachable points from 1" << endl;
    for(int i = 1; i < 10; i++){
        cout << visited[i] << endl;
    }

    int c;
    int i = 9;
    while(parent[i] > 0){
      i = parent[i];
      c++;
    }
    cout << c << endl;
    return 0;
}