Problem8.java

class Node
{
    int data;
    Node left, right;
    public Node(int item)
    {
        data = item;
        left = right = null;
    }
}

class Count
{
    int count = 0;
}

class BinaryTree
{
    Node root;
    Count ct = new Count();
    
    boolean countSingleRec(Node node, Count c)
    {
        if(node == null)
            return true;
        
        boolean left = countSingleRec(node.left, c);
        boolean right = countSingleRec(node.right, c);
        
        if(left == false || right == false)
            return false;
            
        if(node.left  != null && node.data != node.left.data)
            return false;
        if(node.right != null && node.data != node.right.data)
            return false;
            
        c.count++;
        return true;
    }
    
    int countSingle()
    {
        return countSingle(root);
    }
    
    int countSingle(Node node)
    {
        countSingleRec(node, ct);
        return ct.count;
    }
}


public class Main
{
	public static void main(String[] args) {
		BinaryTree tree = new BinaryTree();
        tree.root = new Node(5); 
        tree.root.left = new Node(4); 
        tree.root.right = new Node(5); 
        tree.root.left.left = new Node(4); 
        tree.root.left.right = new Node(4); 
        tree.root.right.right = new Node(5); 
        
        System.out.println(" unival subtrees : " + tree.countSingle());   
	}
}