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check if binary tree is min heap

Excited Eagle answered on April 16, 2023 Popularity 6/10 Helpfulness 1/10

answer check if binary tree is min heap

check if binary tree is min heap

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import java.util.LinkedList;
import java.util.Queue;
     
    class BinaryTreeCheckForMinHeap{
    
        static class Node {
    
            int value;
            Node left, right;
    
            Node(int value) {
                this.value = value;
                this.left = null;
                this.right = null;
            }
        }
     
    
        public static boolean isMinHeap(Node node) {
            // an empty tree is considered as a min heap
            if (node == null) {
                return true;
            }
    
            // We have to check two conditions:
            // 1. The Given Binary Tree is Complete
            // 2. The Given Binary Tree follows the Min Heap Property
            return (isCompleteTree(node) && isMinHeapCall(node));
        }
     
        public static boolean isCompleteTree(Node node) {
            // empty tree is considered as a complete binary tree
            if (node == null) {
                return true;
            }
    
            // Do a BFS traversal for the binary tree and check if it is complete or not
            Queue nodesQueue = new LinkedList();
            nodesQueue.add(node);
            boolean isHeapEnded = false;
         
            while (nodesQueue.size() > 0) {
                Node currentNode = nodesQueue.poll();
    
                if (currentNode == null) {
                    // When we get the first null node, then it should be end of the heap
                    // All the nodes after we get first null node should be also null
                    isHeapEnded = true;
                } else {
                    if (isHeapEnded) {
                        // If we get a node which is not null after getting a null node then it cannot
                        // be a complete binary tree
                        return false;
                    }
    
                    nodesQueue.add(currentNode.left);
                    nodesQueue.add(currentNode.right);
                }
            }
         
            // If we are out of the loop then the binary tree is a complete tree
            return true;
         }
     
        public static boolean isMinHeapCall(Node node) {
            // Base Case: Since a null node is a empty min heap
            if (node == null) {
                return true;
            }
    
            if (node.left != null && node.left.value < node.value) {
                // Return false, as left child has value less than the parent
                return false;
            }
    
            if (node.right != null && node.right.value < node.value) {
                // Return false, as right child has value less than the parent
                return false;
            }
    
            // Check both the child nodes recursively
            return (isMinHeapCall(node.left) && isMinHeapCall(node.right));
        }
     
        public static void main(String[] args) {
            // Example 1: A Min Heap
            Node tree1 = new Node(1);
            tree1.left = new Node(3);
            tree1.right = new Node(2);
            tree1.left.left = new Node(4);
            tree1.left.right = new Node(6);
            tree1.right.left = new Node(5);
    
            if (isMinHeap(tree1)) {
                System.out.println("The Example 1 is a MinHeap");
            } else {
                System.out.println("The Example 1 is not a MinHeap");
            }
    
            // Example 2: A complete tree but not a min heap
            Node tree2 = new Node(8);
            tree2.left = new Node(2);
            tree2.right = new Node(6);
            tree2.left.left = new Node(12);
            tree2.left.right = new Node(11);
            tree2.right.left = new Node(10);
    
            if (isMinHeap(tree2)) {
                System.out.println("The Example 2 is a MinHeap");
            } else {
                System.out.println("The Example 2 is not a MinHeap");
            }
    
            // Example 2: A Non Complete Binary tree
            // In the below tree tree3.left.left is null so it is not a complete binary tree.
            Node tree3 = new Node(1);
            tree3.left = new Node(2);
            tree3.right = new Node(3);
            tree3.left.right = new Node(4);
            tree3.right.left = new Node(5);
    
            if (isMinHeap(tree3)) {
                System.out.println("The Example 3 is a MinHeap");
            } else {
                System.out.println("The Example 3 is not a MinHeap");
            }
        }
    
  }

Popularity 6/10 Helpfulness 1/10 Language whatever

Source: Grepper

Tags: binary-tree min-heap whatever

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Contributed on Apr 16 2023

Excited Eagle

0 Answers Avg Quality 2/10

check if binary tree is min heap

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