From e46bb0a2634b3b58ec136793b8b3821f150bac0c Mon Sep 17 00:00:00 2001
From: NasreenParween <nasreen999786@gmail.com>
Date: Thu, 7 Jul 2022 17:47:46 +0530
Subject: [PATCH] Breadth-First Search

---
 DAA_BFS.cpp | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)
 create mode 100644 DAA_BFS.cpp

diff --git a/DAA_BFS.cpp b/DAA_BFS.cpp
new file mode 100644
index 0000000..3548b5d
--- /dev/null
+++ b/DAA_BFS.cpp
@@ -0,0 +1,156 @@
+#include <iostream>
+#include<stdlib.h>
+using namespace std;
+#define max 30
+template<class t>
+class node
+{
+	public:
+	node *next;
+	int vertex;
+};
+template<class t>
+class graphq
+{
+	public:
+	int data[max];
+	int rear,front;
+	void enqueue(graphq *, int);
+	int dequeue(graphq *);
+	int empty(graphq *);
+	int full(graphq *);
+	void BFS(int);
+	void readgraph();
+	void insert(int vi, int vj);
+	int discovered[max];
+	int layer[max],parent[max];
+	node<t> *heads[max];
+	int n;
+};
+
+
+template<class t>
+void graphq<t>::BFS(int v)
+{
+	int w,i;
+	graphq Q;
+	node<t> *p;
+	Q.rear=Q.front=-1;
+	for(i=1;i<=n;i++)
+	discovered[i]=0;
+	enqueue(&Q,v);
+	int ly=0;
+	layer[v]=ly;
+	parent[v]=-1;
+	cout<<"\nVisit "<<v;
+	cout<<"\tand its parent is none and layer is : "<<layer[v];
+	discovered[v]=1;
+	ly=1;
+	while(!empty(&Q))
+	{
+		v=dequeue(&Q);
+		for(p=heads[v];p!=NULL;p=p->next)
+		{
+			w=p->vertex;
+			if(discovered[w]==0)
+			{
+				parent[w]=v;
+				layer[w]=layer[parent[w]]+1;
+				enqueue(&Q,w);
+				discovered[w]=1;
+				cout<<"\nVisit "<<w;
+				cout<<"\nParent of "<<w<<" is "<<parent[w]<<" and its layer is "<<layer[w];
+				}
+		}
+	}
+}
+template<class t>
+int graphq<t>::empty(graphq *p)
+{
+	if(p->rear==-1)
+	return(1);
+	return(0);
+}
+template<class t>
+int graphq<t>::full(graphq *p)
+{
+	if(p->rear==max-1)
+	return(1);
+	return(0);
+}
+template<class t>
+void graphq<t>::enqueue(graphq *p, int x)
+{
+	if(p->rear==-1)
+	{
+		p->rear=p->front=0;
+		p->data[p->rear]=x;
+	}
+	else
+	{
+		p->rear=p->rear+1;
+		p->data[p->rear]=x;
+	}
+}
+template<class t>
+int graphq<t>::dequeue(graphq *p)
+{
+	int x;
+	x=p->data[p->front];
+	if(p->rear==p->front)
+	{
+		p->rear=-1;
+		p->front=-1;
+	}
+	else
+	p->front=p->front+1;
+	return(x);
+}
+template<class t>
+void graphq<t>::readgraph()
+{
+	int i,vi,vj, nofedges;
+	cout<<"\nEnter the number of vertices : ";
+	cin>>n;
+	for(i=0;i<n;i++)
+	heads[i]=NULL;
+	cout<<"\nEnter the number of edges : ";
+	cin>>nofedges;
+	for(i=0;i<nofedges;i++)
+	{
+		cout<<"\nEnter an edge (u,v) : ";
+		cin>>vi>>vj;
+		insert(vi,vj);
+		insert(vj,vi);
+	}
+}
+template<class t>
+void graphq<t>::insert(int vi, int vj)
+{
+	node<t>*P;
+	node<t>*Q;
+	Q=new node<t>;
+	Q->vertex=vj;
+	Q->next=NULL;
+	if(heads[vi]==NULL)
+	heads[vi]=Q;
+	else
+	{
+		P=heads[vi];
+		while(P->next!=NULL)
+		P=P->next;
+		P->next=Q;
+	}
+}
+int main()
+{
+	int i;
+	graphq<int>gq;
+	cout<<"\nCreate a node";
+	gq.readgraph();
+	cout<<"\nBFS";
+	cout<<"\nStarting node number : ";
+	cin>>i;
+	gq.BFS(i);
+	return 0;
+}