Create 0129-sum-root-to-leaf-numbers.kt

Author: a93a

kotlin/0129-sum-root-to-leaf-numbers.kt

@@ -0,0 +1,25 @@
+class Solution {
+    fun sumNumbers(root: TreeNode?): Int {
+        var res = 0
+
+        fun dfs(root: TreeNode?, current: Int) {
+            root?: return
+
+            var new = current * 10
+            new += root.value
+
+            if(root.left == null && root.right == null) {
+                res += new
+                return
+            }
+
+            dfs(root.left, new)
+            dfs(root.right, new)
+        }
+        
+        dfs(root, 0)
+        return res
+    }
+
+    val TreeNode.value get()= this.`val`
+}