Merge pull request #2468 from DaleStudy/week4

[DaleSeo] WEEK 4 Solutions

Author: DaleSeo

maximum-depth-of-binary-tree/DaleSeo.rs

@@ -0,0 +1,19 @@
+// TC: O(n)
+// SC: O(n)
+use std::cell::RefCell;
+use std::rc::Rc;
+
+impl Solution {
+    pub fn max_depth(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
+        match root {
+            None => 0,
+            Some(node) => {
+                let node = node.borrow();
+                1 + std::cmp::max(
+                    Self::max_depth(node.left.clone()),
+                    Self::max_depth(node.right.clone()),
+                )
+            }
+        }
+    }
+}