Count of Nodes whose both immediate children are its prime factors
Given a Binary Tree, the task is to print the count of nodes having both children and both of them are its prime factors.
Examples:
Input:
1
/ \
15 20
/ \ / \
3 5 4 2
\ /
2 3
Output: 1
Explanation:
Children of 15 (3, 5) are prime factors of 15
Input:
7
/ \
210 14
/ \ \
70 14 30
/ \ / \
2 5 3 5
/
23
Output: 2
Explanation:
Children of 70 (2, 5) are prime factors of 70
Children of 30 (3, 5) are prime factors of 30
Approach:
- Traverse the given Binary Tree and for each node, check both the children exists or not.
- If both the children exist, check if each child is a prime factor of this node or not.
- Keep the count of such nodes and print it at the end.
- In order to check if a factor is prime, we will use Sieve to precompute the prime numbers to do the checking in O(1).
Below is the implementation of the above approach.
C++
// C++ program for Counting nodes// whose immediate children are its factors #include <bits/stdc++.h>using namespace std; int N = 1000000; // To store all prime numbersvector<int> prime; void SieveOfEratosthenes(){ // Create a boolean array "prime[0..N]" // and initialize all entries it as true. // A value in prime[i] will finally // be false if i is Not a prime, else true. bool check[N + 1]; memset(check, true, sizeof(check)); for (int p = 2; p * p <= N; p++) { // If prime[p] is not changed, // then it is a prime if (check[p] == true) { prime.push_back(p); // Update all multiples of p // greater than or equal to // the square of it // numbers which are multiples of p // and are less than p^2 // are already marked. for (int i = p * p; i <= N; i += p) check[i] = false; } }} // A Tree nodestruct Node { int key; struct Node *left, *right;}; // Utility function to create a new nodeNode* newNode(int key){ Node* temp = new Node; temp->key = key; temp->left = temp->right = NULL; return (temp);} // function to check and print if// immediate children of a node// are its factors or notbool areChilrenPrimeFactors(struct Node* parent, struct Node* a, struct Node* b){ if (prime[a->key] && prime[b->key] && (parent->key % a->key == 0 && parent->key % b->key == 0)) return true; else return false;} // Function to get the count of full Nodes in// a binary treeunsigned int getCount(struct Node* node){ // If tree is empty if (!node) return 0; queue<Node*> q; // Initialize count of ful/l nodes // having children as their factors int count = 0; // Do level order traversal // starting from root q.push(node); while (!q.empty()) { struct Node* temp = q.front(); q.pop(); if (temp->left && temp->right) { if (areChilrenPrimeFactors( temp, temp->left, temp->right)) count++; } if (temp->left != NULL) q.push(temp->left); if (temp->right != NULL) q.push(temp->right); } return count;} // Function to find total no of nodes// In a given binary treeint findSize(struct Node* node){ // Base condition if (node == NULL) return 0; return 1 + findSize(node->left) + findSize(node->right);} // Driver Codeint main(){ /* 10 / \ 2 5 / \ 18 12 / \ / \ 2 3 3 2 / 7 */ // Create Binary Tree as shown Node* root = newNode(10); root->left = newNode(2); root->right = newNode(5); root->right->left = newNode(18); root->right->right = newNode(12); root->right->left->left = newNode(2); root->right->left->right = newNode(3); root->right->right->left = newNode(3); root->right->right->right = newNode(2); root->right->right->right->left = newNode(7); // To save all prime numbers SieveOfEratosthenes(); // Print all nodes having // children as their factors cout << getCount(root) << endl; return 0;} |
Java
// Java program for Counting nodes// whose immediate children are its factorsimport java.util.*; class GFG{ static int N = 1000000; // To store all prime numbersstatic Vector<Integer> prime = new Vector<Integer>(); static void SieveOfEratosthenes(){ // Create a boolean array "prime[0..N]" // and initialize all entries it as true. // A value in prime[i] will finally // be false if i is Not a prime, else true. boolean []check = new boolean[N + 1]; Arrays.fill(check, true); for (int p = 2; p * p <= N; p++) { // If prime[p] is not changed, // then it is a prime if (check[p] == true) { prime.add(p); // Update all multiples of p // greater than or equal to // the square of it // numbers which are multiples of p // and are less than p^2 // are already marked. for (int i = p * p; i <= N; i += p) check[i] = false; } }} // A Tree nodestatic class Node { int key; Node left, right;}; // Utility function to create a new nodestatic Node newNode(int key){ Node temp = new Node(); temp.key = key; temp.left = temp.right = null; return (temp);} // function to check and print if// immediate children of a node// are its factors or notstatic boolean areChilrenPrimeFactors(Node parent, Node a, Node b){ if (prime.get(a.key) != null && prime.get(b.key) != null && (parent.key % a.key == 0 && parent.key % b.key == 0)) return true; else return false;} // Function to get the count of full Nodes in// a binary treestatic int getCount(Node node){ // If tree is empty if (node == null) return 0; Queue<Node> q = new LinkedList<>(); // Initialize count of ful/l nodes // having children as their factors int count = 0; // Do level order traversal // starting from root q.add(node); while (!q.isEmpty()) { Node temp = q.peek(); q.remove(); if (temp.left!=null && temp.right != null) { if (areChilrenPrimeFactors( temp, temp.left, temp.right)) count++; } if (temp.left != null) q.add(temp.left); if (temp.right != null) q.add(temp.right); } return count;} // Function to find total no of nodes// In a given binary treestatic int findSize(Node node){ // Base condition if (node == null) return 0; return 1 + findSize(node.left) + findSize(node.right);} // Driver Codepublic static void main(String[] args){ /* 10 / \ 2 5 / \ 18 12 / \ / \ 2 3 3 2 / 7 */ // Create Binary Tree as shown Node root = newNode(10); root.left = newNode(2); root.right = newNode(5); root.right.left = newNode(18); root.right.right = newNode(12); root.right.left.left = newNode(2); root.right.left.right = newNode(3); root.right.right.left = newNode(3); root.right.right.right = newNode(2); root.right.right.right.left = newNode(7); // To save all prime numbers SieveOfEratosthenes(); // Print all nodes having // children as their factors System.out.print(getCount(root) +"\n"); }} // This code is contributed by Rajput-Ji |
C#
// C# program for Counting nodes// whose immediate children are its factorsusing System;using System.Collections.Generic; class GFG{ static int N = 1000000; // To store all prime numbersstatic List<int> prime = new List<int>(); static void SieveOfEratosthenes(){ // Create a bool array "prime[0..N]" // and initialize all entries it as true. // A value in prime[i] will finally // be false if i is Not a prime, else true. bool []check = new bool[N + 1]; for (int i = 0; i <= N; i += 1){ check[i] = true; } for (int p = 2; p * p <= N; p++) { // If prime[p] is not changed, // then it is a prime if (check[p] == true) { prime.Add(p); // Update all multiples of p // greater than or equal to // the square of it // numbers which are multiples of p // and are less than p^2 // are already marked. for (int i = p * p; i <= N; i += p) check[i] = false; } }} // A Tree nodeclass Node { public int key; public Node left, right;}; // Utility function to create a new nodestatic Node newNode(int key){ Node temp = new Node(); temp.key = key; temp.left = temp.right = null; return (temp);} // function to check and print if// immediate children of a node// are its factors or notstatic bool areChilrenPrimeFactors(Node parent, Node a, Node b){ if (prime.Contains(a.key)&& prime.Contains(b.key) && (parent.key % a.key == 0 && parent.key % b.key == 0)) return true; else return false;} // Function to get the count of full Nodes in// a binary treestatic int getCount(Node node){ // If tree is empty if (node == null) return 0; List<Node> q = new List<Node>(); // Initialize count of ful/l nodes // having children as their factors int count = 0; // Do level order traversal // starting from root q.Add(node); while (q.Count!=0) { Node temp = q[0]; q.RemoveAt(0); if (temp.left!=null && temp.right != null) { if (areChilrenPrimeFactors( temp, temp.left, temp.right)) count++; } if (temp.left != null) q.Add(temp.left); if (temp.right != null) q.Add(temp.right); } return count;} // Function to find total no of nodes// In a given binary treestatic int findSize(Node node){ // Base condition if (node == null) return 0; return 1 + findSize(node.left) + findSize(node.right);} // Driver Codepublic static void Main(String[] args){ /* 10 / \ 2 5 / \ 18 12 / \ / \ 2 3 3 2 / 7 */ // Create Binary Tree as shown Node root = newNode(10); root.left = newNode(2); root.right = newNode(5); root.right.left = newNode(18); root.right.right = newNode(12); root.right.left.left = newNode(2); root.right.left.right = newNode(3); root.right.right.left = newNode(3); root.right.right.right = newNode(2); root.right.right.right.left = newNode(7); // To save all prime numbers SieveOfEratosthenes(); // Print all nodes having // children as their factors Console.Write(getCount(root) +"\n"); }} // This code is contributed by Rajput-Ji |
Output:
3
