Create CountofSingleValuedSubtrees.java

CountofSingleValuedSubtrees.java

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+// Java program to find count of single valued subtrees
+
+/* Class containing left and right child of current
+node and key value*/
+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();
+
+	// This function increments count by number of single
+	// valued subtrees under root. It returns true if subtree
+	// under root is Singly, else false.
+	boolean countSingleRec(Node node, Count c)
+	{
+		// Return false to indicate NULL
+		if (node == null)
+			return true;
+
+		// Recursively count in left and right subtrees also
+		boolean left = countSingleRec(node.left, c);
+		boolean right = countSingleRec(node.right, c);
+
+		// If any of the subtrees is not singly, then this
+		// cannot be singly.
+		if (left == false || right == false)
+			return false;
+
+		// If left subtree is singly and non-empty, but data
+		// doesn't match
+		if (node.left != null && node.data != node.left.data)
+			return false;
+
+		// Same for right subtree
+		if (node.right != null && node.data != node.right.data)
+			return false;
+
+		// If none of the above conditions is true, then
+		// tree rooted under root is single valued, increment
+		// count and return true.
+		c.count++;
+		return true;
+	}
+
+	// This function mainly calls countSingleRec()
+	// after initializing count as 0
+	int countSingle()
+	{
+		return countSingle(root);
+	}
+	int countSingle(Node node)
+	{
+		// Recursive function to count
+		countSingleRec(node, ct);
+		return ct.count;
+	}
+
+	// Driver program to test above functions
+	public static void main(String args[])
+	{
+		/* Let us construct the below tree
+				5
+			/ \
+			4	 5
+		/ \	 \
+		4 4	 5 */
+		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("The count of single valued sub trees is : "
+											+ tree.countSingle());
+	}
+}
+
+// This code has been contributed by Mayank Jaiswal