Program to count leaf nodes in a binary tree

Problem link

Recursion Steps:

  • If node is null return zero
  • If left and right nodes are null return 1
  • Return count of leaves for left and right subtrees

Code:


public class CountLeaves {
    Node root;
   
    int countLeaves(Node node){
       
        if(node == null)
            return 0;
       
        if(node.left == null && node.right == null)
            return 1;
       
        return countLeaves(node.left)+countLeaves(node.right);
    }
   
    public static void main(String[] args){
        CountLeaves tree = new CountLeaves();
       
        tree.root = new Node(1);
        tree.root.right = new Node(2);
        tree.root.left = new Node(3);
        tree.root.right.left = new Node(4);
        tree.root.right.right = new Node(5);
       
        System.out.println("No. of Leaves: "+ tree.countLeaves(tree.root));
    }
   

}



Output:

No. of Leaves: 3



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