Special two digit numbers in a Binary Search Tree

Given a Binary Search Trees, task is to count the number of nodes which are having special two digit numbers.

Prerequisite : Special Two Digit Number | Binary Search Tree

Examples :

Input : 15 7 987 21
Output : 0

Input : 19 99 57 1 22
Output : 2

Algorithm : Iterate through each node of tree recursively with a variable count, and check each node’s data for special two digit number. If it is then increment the variable count. At the end, return count.

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// C program to count number of nodes in
// BST containing two digit special number
#include <stdio.h>
#include <stdlib.h>
  
// A Tree node
struct Node
{
    struct Node *left;
    int info;
    struct Node *right;
};
  
// Function to create a new node
void insert(struct Node **rt, int key)
{
    if(*rt == NULL)
    {
        (*rt) = (struct Node *)malloc(sizeof(struct Node));
        (*rt) -> left = NULL;
        (*rt) -> right = NULL;
        (*rt) -> info = key;
    }
    else if(key < ((*rt) -> info))
        insert(&((*rt) -> left), key);
    else
        insert(&(*rt) -> right, key);
}
  
// Function to find if number
// is special or not
int check(int num)
{
    int sum = 0, i = num, sum_of_digits, prod_of_digits ;
      
    // Check if number is two digit or not
    if(num < 10 || num > 99)
        return 0;
    else
    {
        sum_of_digits = (i % 10) + (i / 10);
        prod_of_digits = (i % 10) * (i / 10);
        sum = sum_of_digits + prod_of_digits;
    }
      
    if(sum == num)
        return 1;
    else
        return 0;
}
  
// Function to count number of special two digit number
void countSpecialDigit(struct Node *rt, int *c)
{
    int x;
    if(rt == NULL)
        return;
    else
    {
        x = check(rt -> info);
        if(x == 1)
            *c = *c + 1;
        countSpecialDigit(rt -> left, c);
        countSpecialDigit(rt -> right, c);
    }
}
  
// Driver program to test
int main()
{
    struct Node *root = NULL;
      
    // Initialize result
    int count = 0;
      
    // Function call to insert() to insert nodes
    insert(&root, 50);
    insert(&root, 29);
    insert(&root, 59);
    insert(&root, 19);
    insert(&root, 53);
    insert(&root, 556);
    insert(&root, 56);
    insert(&root, 94);
    insert(&root, 13);
  
    // Function call, to check each node for 
    // special two digit number
    countSpecialDigit(root, &count);
    printf("%d", count);
      
    return 0;
}

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Output:

3

Time Complexity : O(N), where N is the number of nodes in Tree.

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