POST ORDER TRAVERSAL -- HACKERRANK SOLUTIONS

 

Complete the  function in the editor below. It received  parameter: a pointer to the root of a binary tree. It must print the values in the tree's postorder traversal as a single line of space-separated values.

Input Format

Our test code passes the root node of a binary tree to the  function.

Constraints

 Nodes in the tree  

Output Format

Print the tree's postorder traversal as a single line of space-separated values.

Sample Input

     1
      \
       2
        \
         5
        /  \
       3    6
        \
         4

Sample Output

4 3 6 5 2 1 

Explanation

The postorder traversal is shown.

Solution

#include <stdio.h>

#include <string.h>

#include <math.h>

#include <stdlib.h>

struct node {

    

    int data;

    struct node *left;

    struct node *right;

  

};

struct node* insert( struct node* root, int data ) {

        

    if(root == NULL) {

    

        struct node* node = (struct node*)malloc(sizeof(struct node));

        node->data = data;

        node->left = NULL;

        node->right = NULL;

        return node;

      

    } else {

      

        struct node* cur;

        

        if(data <= root->data) {

            cur = insert(root->left, data);

            root->left = cur;

        } else {

            cur = insert(root->right, data);

            root->right = cur;

        }

    

        return root;

    }

}

/* you only have to complete the function given below.  

node is defined as  

struct node {

    

    int data;

    struct node *left;

    struct node *right;

  

};

*/

void postOrder( struct node *root) {

    struct node *head=root;

    if(head!=NULL){

        postOrder(head->left);

        postOrder(head->right);

        printf("%d ",head->data);

    }

}

int main() {

  

    struct node* root = NULL;

    

    int t;

    int data;

    scanf("%d", &t);

    while(t-- > 0) {

        scanf("%d", &data);

        root = insert(root, data);

    }

  

    postOrder(root);

    return 0;

}