Spiral Order traversal of Tree in C

March 10, 2023

Spiral Order Traversal of Binary Tree in C

Given a Tree and we need to print the spiral order traversal of the given tree. By spiral Order Traversal We mean that alternate levels should be printed in alternate order .

Example – Level 0 to be printed left to right
Level 1 from right to left, and so on.

Spiral Order Traversal of Binary Tree In C

Algorithm :

Create a Boolean variable ltr which is used to change printing order of levels.
If ltr is 1 then printGivenLevel() prints nodes from left to right else from right to left. Value of ltr is flipped in each iteration to change the order.
Function to print level order traversal :
- printSpiral(tree) set ltr to 0;
- Run a loop from 0 to height -1
- printGivenLevel(tree, d, ltr);
- ltr ~= ltr /*flip ltr*/
To print the nodes is :if tree is NULL then return;
- if level is 1, then print(tree->data);
- else if level greater than 1, then
- if(ltr) printGivenLevel(tree->left, level-1, ltr) and printGivenLevel(tree->right, level-1, ltr);
- else printGivenLevel(tree->right, level-1, ltr) and printGivenLevel(tree->left, level-1, ltr);

Find size of the Binary tree

Find the height of binary tree

Find maximum in binary tree

Check If binary tree if Foldable or not

check whether tree is Symmetric

Code in C for Spiral Order Traversal

Run

#include<stdbool.h>
#include<stdio.h>
#include<stdlib.h>

struct node
{
  int data;
  struct node *left;
  struct node *right;
};

void printGivenLevel (struct node *root, int level, int ltr);
int height (struct node *node);
struct node *newNode (int data);

void printSpiral (struct node *root)
{
  int h = height (root);
  int i;

  bool ltr = false;
  for (i = 1; i <= h; i++)
    {
      printGivenLevel (root, i, ltr);

      ltr = !ltr;
    }
}

void printGivenLevel (struct node *root, int level, int ltr)
{
  if (root == NULL)
    return;
  if (level == 1)
    printf ("%d ", root->data);
  else if (level > 1)
    {
      if (ltr)
	{
	  printGivenLevel (root->left, level - 1, ltr);
	  printGivenLevel (root->right, level - 1, ltr);
	}
      else
	{
	  printGivenLevel (root->right, level - 1, ltr);
	  printGivenLevel (root->left, level - 1, ltr);
	}
    }
}

int height (struct node *node)
{
  if (node == NULL)
    return 0;
  else
    {
      int lheight = height (node->left);
      int rheight = height (node->right);

      if (lheight > rheight)
	return (lheight + 1);
      else
	return (rheight + 1);
    }
}

struct node *newNode (int data)
{
  struct node *node = (struct node *) malloc (sizeof (struct node));
  node->data = data;
  node->left = NULL;
  node->right = NULL;

  return (node);
}

int main ()
{
  struct node *root = newNode (10);
  root->left = newNode (20);
  root->right = newNode (30);
  root->left->left = newNode (40);
  root->left->right = newNode (50);
  root->right->left = newNode (60);
  root->right->right = newNode (70);

  printf ("Spiral Order traversal of binary tree is \n");

  printSpiral (root);

  return 0;
}

Output

Spiral Order traversal of binary tree is
10 20 30 70 60 50 40

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