Algorithm

  1. Node Definition:

    • Define a class TreeNode with integer value and left and right child references.

  2. Leaf Node Count Algorithm:

    • Create a class TreeLeafCounter.
    • Define a method countLeafNodes that takes a TreeNode as a parameter.
    • If the node is null, return 0.
    • If the node is a leaf (both left and right children are null), return 1.
    • Recursively call countLeafNodes on the left and right children.
    • Return the sum of leaf counts from the left and right subtrees.

  3. Example Usage:

    • Create a sample tree with instances of TreeNode.
    • Instantiate TreeLeafCounter.
    • Call countLeafNodes with the root of the tree to get the count of leaf nodes.

 

Code Examples

#1 Code Example- Java Program to count the number of leaf nodes in a tree

Code - Java Programming

class Node {
  int item;
  Node left, right;

  public Node(int key) {
  item = key;
  left = right = null;
  }
}

class Main {
  // root of Tree
  Node root;

  Main() {
  root = null;
  }

  // method to count leaf nodes
  public static int countLeaf(Node node) {
    if(node == null) {
      return 0;
    }

    // if left and right of the node is null
    // it is leaf node
    if (node.left == null && node.right == null) {
      return 1;
    }
    else {
      return countLeaf(node.left) + countLeaf(node.right);
    }
  }

  public static void main(String[] args) {

    // create an object of Tree
    Main tree = new Main();

    // create nodes of tree
    tree.root = new Node(5);
    tree.root.left = new Node(3);
    tree.root.right = new Node(8);

    // create child nodes of left child
    tree.root.left.left = new Node(2);
    tree.root.left.right = new Node(4);

    // create child nodes of right child
    tree.root.right.left = new Node(7);
    tree.root.right.right = new Node(9);

    // call method to count leaf nodes
    int leafNodes = countLeaf(tree.root);
    System.out.println("Total Leaf Nodes = " + leafNodes);
  }
}
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Output

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Total Leaf Nodes = 4
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Demonstration

Java Programing Example to Count number of leaf nodes in a tree-DevsEnv