DFS

#include <iostream>
#include <queue>
#include <stack>
#include <string.h>
#include <cstdio>
/****************************/
/* (A)------------(B)*/
/*  |              |      input like AB (vertices 4, edges4)
 *  |              |                 AC
 * (C)------------(D)                CD
 *                                   BD
/*                    */



using namespace std;

stack<int> number;


int graph[50][50] = {0};

int edges, vertices;

int visited[100] = {0};

void graphInput(){

    cout<<"Input number of vertices"<<endl;
    cin>>vertices;
    cout<<"Input number of edges"<<endl;
    cin>>edges;
    char v1, v2;


    for(int i=0; i<edges; i++){

            cin>>v1>>v2;
            graph[v1-65][v2-65]=1;
            graph[v2-65][v1-65]=1;

        }

    }

bool isVisited(int v){

    for(int i=0; i<100; i++){
        if(visited[i] == v)
            return true;
    }
return false;
}
void BFS(){
    number.push(0);
    int t,index=0;
    while(!number.empty()){

        t = number.top();
        number.pop();

        if( isVisited(t) != true ){
            visited[index++] = t;


            for(int i =0; i<26; i++){

            if(graph[t][i]){

                if(isVisited(i) != true ){
                    number.push(i);
                    //cout<<i;
                    }
                }

            }

        } /*end if*/
    }

}


void displayGraph(){
    for(int i=0; i<vertices; i++){
            printf("%c->", i+65);
        for(int j=0; j<26; j++){
                if(graph[i][j])
                    printf("%c", j+65);
            }

            cout<<endl;

        }

}

int main(int argc, char **argv)
{
    for(int i =0; i<100; i++)
        visited[i] =-1;

    graphInput();




    displayGraph();
    BFS();

    for(int i=0; i<100; i++){

        if(visited[i] !=-1){
            printf("%c", 65+visited[i]);

        }
    }



    return 0;
}