BFS

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <string.h>
using  namespace std;
struct list {
    int val;
    struct list * next;
};


typedef struct list node;

node *Insert(node *head, int edg){

        node *temp;
        temp = new node();
        temp->val = edg;
        temp->next = head;
        return temp;

}


void BFS(node *graph[], int vertices, int parent[], int level[]){

        int flag=1, par, lev=0,i;
        level[1] = lev;
        node *temp;
        while(flag){
            flag=0;

            for(i=1; i<=vertices; i++){

                if(level[i] == lev){
                    flag = 1;
                    temp = graph[i];
                    par=i;


                    while(temp!=NULL){

                            if(level[temp->val] !=-1){
                                temp = temp->next;
                                continue;
                            }

                            level[temp->val] = lev+1;
                            cout<<"x";
                            parent[temp->val] = par;
                            temp=temp->next;
                        }
                }

            }

        ++lev;
    }


}

int main(){
int vertices, v1,v2,i, edges;

    cout<<"enter number of vertices:";
        cin>>vertices;
    cout<<"number of edges:";
        cin>>edges;

    int level[vertices+1] , parent[vertices+1];

    node *vertex[vertices+1] = {NULL};


    for(i=0; i<=vertices; i++){

        level[i] = -1;
        parent[i] = 0;
        }

    for(i=1; i<=vertices; i++){

        cin>>v1>>v2;

        vertex[v1] = Insert(vertex[v1], v2);
        vertex[v2] = Insert(vertex[v2], v1);


        }

    for (i = 1; i <= vertices; ++i) {
        printf("%d -> ", i);

         node * temp = vertex[i];

        while (temp != NULL) {
            printf("%d -> ", temp->val);
            temp = temp->next;
        }

        printf("NULL\n");
    }







    BFS(vertex, vertices,parent,level);

    for (i = 1; i <= vertices; ++i) {
        printf("Level of Node %d is %d, Parent is %d\n", i, level[i], parent[i]);
    }

    return 0;
}