solve problem

Author: delight010

maximum-depth-of-binary-tree/delight010.swift

@@ -0,0 +1,26 @@
+class Solution {
+    func maxDepth(_ root: TreeNode?) -> Int {
+        if root == nil {
+            return 0
+        }
+        
+        var level = 0
+        var stack: [(TreeNode?, Int)] = [(root, 1)]
+        
+        while !stack.isEmpty {
+            let (current, count) = stack.removeLast()
+            if current?.left == nil && current?.right == nil {
+                level = max(level, count)
+            }
+            if let right = current?.right {
+                stack.append((right, count + 1))
+            }
+            if let left = current?.left {
+                stack.append((left, count + 1))
+            }
+        }
+        
+        return level
+    }
+}
+