Check If binary tree is Foldable or not in C

March 14, 2023

Tree is Foldable or Not?

Here, in this page we will write a C program to check whether the given binary tree is foldable or not. A Tree is said to be foldable if its left and right counter part can be made to overlap with each other .

Check If binary tree is Foldable or not in C Language

Algorithm :

If tree is empty, then return true.
Convert the left subtree to its mirror image mirror(root->left);
Check if the structure of left subtree and right subtree is same and store the result. res = isStructSame(root->left, root->right);
isStructSame() recursively compares structures of two subtrees and returns true if structures are same
Revert the changes made in step 2 to get the original tree. mirror(root->left);
Return result res stored in step 2.

Check whether two tree are identical

Spiral Order traversal of Tree

check whether tree is Symmetric

Sum of all nodes in Binary Tree

Check for Children-Sum in Binary Tree

Code in C based on above approach

Run

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

#define bool int
#define true 1
#define false 0

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

void mirror (struct node *node);

bool isStructSame (struct node *a, struct node *b);

bool isFoldable (struct node *root)
{
  bool res;

  if (root == NULL)
    return true;

  mirror (root->left);

  res = isStructSame (root->left, root->right);

  mirror (root->left);

  return res;
}

bool isStructSame (struct node * a, struct node * b)
{
  if (a == NULL && b == NULL)
    {
      return true;
    }
  if (a != NULL && b != NULL && isStructSame (a->left, b->left)
      && isStructSame (a->right, b->right))
    {
      return true;
    }

  return false;
}

void mirror (struct node *node)
{
  if (node == NULL)
    return;
  else
    {
      struct node *temp;

      mirror (node->left);
      mirror (node->right);

      temp = node->left;
      node->left = node->right;
      node->right = temp;
    }
}

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 (void)
{
  struct node *root = newNode (10);
  root->left = newNode (20);
  root->right = newNode (30);
  root->right->left = newNode (40);
  root->left->right = newNode (50);

  if (isFoldable (root) == 1)
    {
      printf ("Tree is foldable");
    }
  else
    {
      printf ("Tree is not foldable");
    }


  return 0;
}

Output:

Tree is foldable

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