Language Java 8 1 > import java. io. *; ... 6. Sum of Left Leaves in a Binary Tree 48 49 /* * 50 * public class TreeNode { 51 * int val; Given a non-empty binary tree, return the sum of all left leaves. 52 TreeNode left; 53 TreeNode right; Example: 54 TreeNode (int x) { val = x; } 55 * Input : 56 * / 57 3 static private int sumOfLeftLeaves (TreeNode root) { 58 /* Write your code here */ 9 20 59 60 15 7 61 > public static void main (String args) throws Exception { ... Output: 24 Explanation: summing up every left leaf in the tree gives us: 9 + 15 = 24