diff --git a/java/sum-root-to-leaf-numbers.java b/java/sum-root-to-leaf-numbers.java new file mode 100644 index 0000000..3b47357 --- /dev/null +++ b/java/sum-root-to-leaf-numbers.java @@ -0,0 +1,22 @@ +class Solution { + private boolean isLeaf(TreeNode node) { + return node != null && node.left == null && node.right == null; + } + + private int sumNumbers(TreeNode node, int number) { + if (node == null) { + return 0; + } + + number = 10 * number + node.val; + if (isLeaf(node)) { + return number; + } + + return sumNumbers(node.left, number) + sumNumbers(node.right, number); + } + + public int sumNumbers(TreeNode root) { + return sumNumbers(root, 0); + } +}