Traverse binary tree in Postorder

Write a C++ Program to Traverse binary tree in Postorder. Here’s simple C++ Program to Traverse binary tree in Postorder in C Programming Language.

What is Tree ?

In linear data structure, data is organized in sequential order and in non-linear data structure, data is organized in random order. Tree is a very popular data structure used in wide range of applications.

A tree data structure can be defined as follows…

• Tree is a non-linear data structure which organizes data in hierarchical structure and this is a recursive definition.

A tree data structure can also be defined as follows…

• Tree data structure is a collection of data (Node) which is organized in hierarchical structure and this is a recursive definition.

Every individual element is called as Node. Node in a tree data structure, stores the actual data of that particular element and link to next element in hierarchical structure.

Below is the source code for C++ Program to Traverse binary tree in Postorder which is successfully compiled and run on Windows System to produce desired output as shown below :

SOURCE CODE : :

/*  C++ Program to Traverse binary tree in Postorder  */

#include<iostream>
#include<stdlib.h>
 
using namespace std;
 
class node
{
public:
class node *left;
class node *right;
int data;
};
 
class tree: public node
{
public:
int stk[50],top;
node *root;
tree()
{
root=NULL;
top=0;
}
void insert(int ch)
{
        node *temp,*temp1;
        if(root== NULL)
        {
                root=new node;
                root->data=ch;
                root->left=NULL;
                root->right=NULL;
                return;
        }
        temp1=new node;
        temp1->data=ch;
        temp1->right=temp1->left=NULL;
        temp=search(root,ch);
        if(temp->data>ch)
                temp->left=temp1;
        else
                temp->right=temp1;
 
}
node *search(node *temp,int ch)
{
        if(root== NULL)
        {
                cout <<"no node present";
                return NULL;
        }
        if(temp->left==NULL && temp->right== NULL)
                return temp;
 
        if(temp->data>ch)
             {  if(temp->left==NULL) return temp;
                search(temp->left,ch);}
        else
              { if(temp->right==NULL) return temp;
              search(temp->right,ch);
 
}              }
 
void display(node *temp)
{
        if(temp==NULL)
         return ;
        display(temp->left);
       cout<<temp->data << " ";
        display(temp->right);
}
void postorder( node *root)
{
        node *p;
        p=root;
        top=0;
 
        while(1)
        {
        while(p!=NULL)
        {
                stk[top]=p->data;
                top++;
                if(p->right!=NULL)
                        stk[top++]=-p->right->data;
                p=p->left; 
        }
        while(stk[top-1] > 0 || top==0)
        {
           if(top==0) return;
           cout << stk[top-1] <<" ";
           p=pop(root);
        }
        if(stk[top-1]<0)
        {
          stk[top-1]=-stk[top-1];
          p=pop(root);
      } }
 
}
node * pop(node *p)
{
int ch;
ch=stk[top-1];
if(p->data==ch)
{
top--;
return p;
}
if(p->data>ch)
pop(p->left);
else
pop(p->right);
}
};
int main()
{
        tree t1;
        int ch,n,i;

        while(1)
        {
                cout <<"\n1.INSERT\n2.DISPLAY 3.POSTORDER TRAVERSE\n4.EXIT\nEnter your choice:";
                cin >> ch;
                switch(ch)
                {
                case 1:   cout <<"enter no of elements to insert:";
                          cout<<"\n enter the elements";
                          cin >> n;
                          for(i=1;i<=n;i++)
                          {  cin >> ch;
                             t1.insert(ch);
                          }
                           break;
                case 2:   t1.display(t1.root);break;
                case 3:   t1.postorder(t1.root); break;
                case 4:   exit(1);
                }
        }
        
        return 0;
}

OUTPUT : :

/*  C++ Program to Traverse binary tree in Postorder  */

1.INSERT
2.DISPLAY 3.POSTORDER TRAVERSE
4.EXIT
Enter your choice:1
enter no of elements to insert:
 enter the elements4
1
2
3
4

1.INSERT
2.DISPLAY 3.POSTORDER TRAVERSE
4.EXIT
Enter your choice:2
1 2 3 4 
1.INSERT
2.DISPLAY 3.POSTORDER TRAVERSE
4.EXIT
Enter your choice:3
4 3 2 1 
1.INSERT
2.DISPLAY 3.POSTORDER TRAVERSE
4.EXIT
Enter your choice:4
 
Exit code: 1

Above is the source code and output for C++ Program to Traverse binary tree in Postorder which is successfully compiled and run on Windows System to produce desired output.

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