Printing edges with their type using non recursive DFS (hacktoberfest17#1177)

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This program prints all edges of a given graph with their type: Back , Forward , Cross , Tree using non-recursive DFS.

* Delete PrintingEdgesInGraphWithType.cpp

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This program creates a graph and prints DFS traversal order and finally print all edges with their types by traversing through non recursive DFS

Author: abhardwaj1998

graphs/DFS printing type of edges/PrintingEdgesInGraphWithType.cpp

@@ -0,0 +1,196 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+typedef struct Node{
+	char key;
+	struct Node* next;
+}node;
+
+typedef struct Sta{
+	char data[100];
+	int top;
+}sta;
+
+void Push(sta* s,char k){
+	s->top=s->top+1;
+	if(s->top>99){
+		cout<<"Stack is full. Cannot push "<<k<<endl;
+		return;
+	}
+	s->data[s->top]=k;
+}
+
+char pop(sta* s){
+	if(s->top==-1){
+		cout<<"Stack is empty. Cannot pop."<<endl;
+		return '.';
+	}
+	s->top=s->top-1;
+	return s->data[s->top+1];
+}
+
+node* CreateNode(char key){
+	node* k=new node;
+	k->next=NULL;
+	k->key=key;
+	return k;
+}
+
+void Read_Graph(int n,int e,node** List){
+	char a,b;
+	for(int i=0;i<e;i++){
+		cin>>a>>b;
+		int k=a-'a';
+		node* m=CreateNode(b);
+		if(List[k]==NULL){
+			List[k]=m;
+		}
+		else{
+			node* temp=List[k];
+			if(List[k]->next==NULL || b<List[k]->key){
+				if(List[k]->key<b){
+					List[k]->next=m;
+				}
+				else{
+					m->next=List[k];
+					List[k]=m;
+				}
+			}
+			else{
+				while(temp->next!=NULL && temp->next->key<b){
+					temp=temp->next;
+				}
+				m->next=temp->next;
+				temp->next=m;
+			}
+		}
+	}
+}
+
+void DFS_Non_Recursive(int i,node** List,int* color,char* parent,int n){
+	sta* s=new sta;
+	string ss="";
+	s->top=-1;
+	char d='a'+i;
+	Push(s,d);
+	int p=0;
+	node*temp=NULL;
+	while(s->top!=-1){
+		p=0;
+		i=s->data[s->top]-'a';
+		color[i]=1;
+		temp=List[i];
+		while(temp!=NULL){
+			if(color[temp->key-'a']==0){
+				if(ss.length()!=0){
+					ss+=", ";
+				}
+				ss=ss+"("+s->data[s->top]+","+temp->key+")";
+				//cout<<"("<<s->data[s->top]<<","<<temp->key<<"), ";
+				Push(s,temp->key);
+				p=1;
+				break;
+			}
+			temp=temp->next;
+		}
+		if(p==1){continue;}
+		else{
+			color[i]=2;
+			pop(s);
+		}
+	}
+	cout<<ss;
+}
+
+void DFS(node** List,int* color,char* parent,int n){
+	for(int i=0;i<26;i++){
+		color[i]=0;
+		parent[i]='.';
+	}
+	int p=0;
+	for(int i=0;i<26;i++){
+		if(color[i]==0 && List[i]!=NULL){
+			if(p){cout<<", ";}
+			p=1;
+			DFS_Recursive(i,List,color,parent,n);
+		}
+	}
+	cout<<endl;
+}
+
+void DFS_Enhanced_Non_Recursive(int i,node** List,int* color,char* parent,int* dd,int n){
+	sta* s=new sta;
+	s->top=-1;
+	static int time=0;
+	char d='a'+i;
+	Push(s,d);
+	time++;
+	dd[i]=time;
+	int p=0;
+	node*temp=NULL;
+	while(s->top!=-1){
+		p=0;
+		i=s->data[s->top]-'a';
+		color[i]=1;
+		temp=List[i];
+		while(temp!=NULL){
+			if(temp->key=='.'){}
+			else if(color[temp->key-'a']==0){
+				Push(s,temp->key);
+				time++;
+				dd[temp->key-'a']=time;
+				p=1;
+				temp->key='.';
+				break;
+			}
+			else if(color[temp->key-'a']==1){
+				cout<<"Back Edge: ("<<s->data[s->top]<<","<<temp->key<<")"<<endl;
+			}
+			else{
+				if(dd[i]<dd[temp->key-'a']){
+					cout<<"Forward Edge: ("<<s->data[s->top]<<","<<temp->key<<")"<<endl;
+				}
+				else{
+					cout<<"Cross Edge: ("<<s->data[s->top]<<","<<temp->key<<")"<<endl;
+				}
+			}
+			temp=temp->next;
+		}
+		if(p==1){continue;}
+		else{
+			time++;
+			color[i]=2;
+			pop(s);
+		}
+	}
+}
+
+void DFS_Enhanced(node** List,int* color,char* parent,int n){
+	int* d=new int[26];
+	for(int i=0;i<26;i++){
+		color[i]=0;
+		d[i]=INT_MAX;
+		parent[i]='.';
+	}
+	for(int i=0;i<26;i++){
+		if(color[i]==0 && List[i]!=NULL){
+			DFS_Enhanced_Recursive(i,List,color,parent,d,n);
+		}
+	}
+	cout<<endl;
+}
+
+int main(){
+	int n,e;
+	cin>>n>>e;
+	int* color=new int[26];
+	char* parent=new char[26];
+	node** List=new node*[26];
+	Read_Graph(n,e,List);
+	string* ss;
+	DFS(List,color,parent,n);
+	cout<<"Tree edges:";
+	DFS(List,color,parent,n);
+	DFS_Enhanced(List,color,parent,n);
+	return 0;
+}