implemented level order traversal in binary tree

Author: anishsingh20

Data Structures/Queues/QueueUsing2Stacks.cpp

@@ -41,7 +41,7 @@ void Queue::Dequeue() {
 	}
 
 	//will enter this condition only at the first call to Dequeue() after inserting some data in queue
-	//is stack 2 is empty , only then we transfer all items from stack1 to stack2 
+	//if stack 2 is empty , only then we transfer all items from stack1 to stack2 
 	if(s2.empty()){ 
 
 		//transfering from stack1 to stack2

Data Structures/Trees/Binary Trees/BinrayTree.cpp

@@ -1,5 +1,6 @@
 #include<iostream>
 #include<stack>
+#include<queue>
 
 //IMPLEMENTATION OF A BINARY TREE- a tree which can have atmost i.e <= 2 child nodes
 
@@ -138,18 +139,36 @@ void PostOrderRec(struct BinaryTreeNode *root)
 
 
 
-     
-//void levelOrder(struct BinaryTreeNode *root)
-//{
-//	
-//	
-//	if(root)
-//	{
-//		cout<<root->data;
-//		levelOrder(root,root->left,root->right);
-//	}
-//}     
-     
+ //In level order we will use a queue to store the level+1 nodes in queue    
+void levelOrder(struct BinaryTreeNode *root)
+{
+	struct BinaryTreeNode *temp;
+	queue<BinaryTreeNode *>q;
+	
+	if(!root) return;
+	
+	q.push(root);
+	
+	while(!q.empty())
+	{
+		temp = q.front();
+		q.pop();
+		
+		cout<<temp->data<<" ";
+		
+		//pushing temp's left and right child if any to queue
+		//we will keep (level+1) children in the queue
+		if(temp->left)
+		{
+			q.push(temp->left);
+		}
+		
+		if(temp->right)
+		{
+			q.push(temp->right);
+		}
+	}
+}     //TIME COMPLEXITY = O(n) , SPACE COMPLEXITY = O(n)
 
 int main()
 {
@@ -196,11 +215,13 @@ int main()
 
 	cout<<"Post order traversal outputs-"<<endl;
 	PostOrderRec(root);
-//	
-//	cout<<endl;
-//	
-//	cout<<"Level order traversal-"<<endl;
-//	
+	
+	cout<<endl;
+	
+	cout<<"Level order traversal-"<<endl;
+	
+	levelOrder(root);
+	
 
 
 

STL/map.cpp

@@ -12,28 +12,35 @@ using namespace std;
 
 int main()
 {
-	map<int,string> m;
+	map<string,int> m;
 
-	m.insert(pair <int,string> (1,"Anish"));
-	m.insert(pair <int,string> (2,"mrinal"));
-	m.insert(pair <int,string> (3,"Vaibhav"));
-	m.insert(pair <int,string> (4,"Rasila"));
+	m.insert(pair <string,int> ("Anish",10));
+	m.insert(pair <string,int> ("mrinal",2));
+	m.insert(pair <string,int> ("Vaibhav",3));
+	m.insert(pair <string,int> ("Rasila",4));
 	//can also insert using
-	m.insert(make_pair(10,"Lucky"));	
+//	m.insert(make_pair(10,"Lucky"));
+	string name;
+	int marks;
+	cin>>name;
+	cin>>marks;
+	map<string,int>::iterator i=m.find(name);
+               int new_marks  = (i->second + marks);
+               i->second = new_marks;	
 
-	map<int,string>::iterator i;
+	map<string,int>::iterator it;
 
 
 	//can also do random access using the key value as subscript-O(1)
-	cout<<m[2]<<endl; //prints mrinal
+	cout<<m["Anish"]<<endl; //prints mrinal
 
 
 	//traversing the map using iterator
-	for(i = m.begin(); i != m.end();i++)
+	for(it = m.begin(); it != m.end();it++)
 	{
-		cout<<i->first;
+		cout<<it->first;
 		cout<<" | ";
-		cout<<i->second;
+		cout<<it->second;
 
 		cout<<endl;
 	}
@@ -45,26 +52,32 @@ int main()
 
 	//will erase elements from begin of map till 2nd element , not 3
 	// remove all elements up to element with key = 3 in found
-	 m.erase(m.begin(), m.find(3) );
-	 
-	 for(i = m.begin(); i != m.end();i++)
-	{
-		cout<<i->first;
-		cout<<" | ";
-		cout<<i->second;
-		
-		cout<<endl;
-	}
+//	 m.erase(m.begin(), m.find(3) );
+//	 
+//	 for(i = m.begin(); i != m.end();i++)
+//	{
+//		cout<<i->first;
+//		cout<<" | ";
+//		cout<<i->second;
+//		
+//		cout<<endl;
+//	}
 
 
 	//find() method returns an iterator to key passed as argument
 
-	map<int,string>::iterator i1;
-	i1 = m.find(3);
-	cout<<i1->second; //prints "mrinal"
-	
-	
-	
-	return 0;
+//	map<int,string>::iterator i1;
+//	int n;
+//	cin>>n;
+//	i1 = m.find(n);
+//	if(i1->first) 
+//		cout<<i1->second; //prints "mrinal"
+//		
+//	else 
+//		cout<<"Not found"<<endl;
+//	
+//	
+//	
+//	return 0;
 
 }