Sum Of Left Leaves

Sum Of Left Leaves tree

Find the sum of all left leaves in a given binary tree.

Example:

     3
    / \
   9  20
     /  \
    15   7

There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.

Sum Of Left Leaves Solution

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class SumOfLeftLeaves {
    public int sumOfLeftLeaves(TreeNode root) {
        if(root == null) {
            return 0;
        }

        int total = 0;

        if(root.left != null) {
            if(root.left.left == null && root.left.right == null) {
                total += root.left.val;
            } else {
                total += sumOfLeftLeaves(root.left);
            }
        }

        total += sumOfLeftLeaves(root.right);

        return total;
    }
}
Last modified October 4, 2020