Get the Sum of all left leaves in a Binary tree

Objective: Given a binary tree, find the sum of all the nodes which are left as well as leaves nodes.

Example:

 

Get the Sum of all left leaves in a Binary tree.
Get the Sum of all left leaves in a Binary tree.

 

Approach:

  1. Approach is quite simple.
  2. Do the inorder traversal
  3. check if node if the left child and leaf node.
  4. If yes then add it to the sum.
  5. See the code for more understanding.

Complete Code:


public class LeftLeavesSum {
// Do the inorder traversal
// check if node if the left child and leaf node
// if yes then add it to the sum
public static int leftLeavesSum = 0;
public static void leftSum(Node root, Node parent) {
if (root != null) {
leftSum(root.left, root);
if (root.left == null && root.right == null && parent.left == root) {
leftLeavesSum += root.data;
}
leftSum(root.right, root);
}
}
public static void main(String args[]) {
Node root = new Node(10);
root.left = new Node(5);
root.right = new Node(15);
root.left.left = new Node(10);
root.left.right = new Node(12);
root.left.right.left = new Node(6);
root.right.right = new Node(8);
root.right.right.left = new Node(5);
leftSum(root, root);
System.out.println("Sum of left leaves: " + leftLeavesSum);
}
}
class Node {
int data;
Node left;
Node right;
public Node(int data) {
this.data = data;
this.left = null;
this.right = null;
}
}


Output:

Sum of left leaves: 21