Depth First Search program in C++ with full explanation of each step:

PROGRAM:

#include <iostream.h>
#include <conio.h>
#define MAX_NODE 50
struct node{
    int vertex;
    node *next;
};
node *adj[MAX_NODE]; //For storing Adjacency list of nodes.int totNodes; //No. of Nodes in Graph.////////////Stack Operation\\\int top=-1;
int stack[MAX_NODE];
void push(int item){
     top=top+1;
     stack[top]=item;
}
int pop(){
     int deldata=stack[top];
     top=top-1;
     return(deldata);
}
int is_stk_empty(){
     if(top==-1)
     return(1);
     elsereturn(0);
}
////////////Stack Operation\\\void createGraph(){
    node *newl,*last;
    int neighbours,neighbour_value;
    cout<<"nn---Graph Creation---nn";
    cout<<"Enter total nodes in graph : ";
    cin>>totNodes;
    for(int i=1;i<=totNodes;i++){
        last=NULL;
        cout<<"nEnter no. of nodes in the adjacency list of node "<<i<<"n";
        cout<<"--> That is Total Neighbours of "<<i<<" : ";
        cin>>neighbours;
        for(int j=1;j<=neighbours;j++){
            cout<<"Enter neighbour #"<<j<<" : ";
            cin>>neighbour_value;
            newl=new node;
            newl->vertex=neighbour_value;
            newl->next=NULL;
            if(adj[i]==NULL)
                adj[i]=last=newl;
            else{
                last->next = newl;
                last = newl;
            }
        }
    }
}
void DFS_traversal(){
    node *tmp;
    int N,v,start_node,status[MAX_NODE];//status arr for maintaing status.constint ready=1,wait=2,processed=3; //status of node.
    cout<<"Enter starting node : ";
    cin>>start_node;
    //step 1 : Initialize all nodes to ready state.for(int i=1;i<=totNodes;i++)
        status[i]=ready;
    //step 2 : push the start node in stack and change status.
    push(start_node); //Push starting node into stack.
    status[start_node]=wait; //change it status to wait state.//step 3 : Repeat until stack is empty.while(is_stk_empty()!=1){
        //step 4 : pop the node N of stack.//process N and change the status of N to//be processed state.
        N = pop(); //pop the node from stack.
        status[N]=processed; //status of N to processed.
        cout<<"   "<<N; //displaying processed node.//step 5 : push onto stack all the neighbours of N,//that are in ready state and change their status to//wait state.
        tmp = adj[N];  //for status updation.while(tmp!=NULL){
            v = tmp->vertex;
            if(status[v]==ready){//check status of N's neighbour.
                push(v); //push N's neighbour who are in ready state.
                status[v]=wait; //and make their status to wait state.
            }
            tmp=tmp->next;
        }
    }
}
void main(){
    clrscr();
    cout<<"*****Depth First Search Traversal*****n";
    createGraph();
    cout<<"n===DFS traversal is as under===n";
    DFS_traversal();
    getch();
}