Merge pull request #1754 from Jack-Zhang-1314/patch-15

Update 0104.二叉树的最大深度.md about rust

problems/0104.二叉树的最大深度.md

@@ -200,32 +200,6 @@ public:
 };
 ```
 
-rust:
-```rust
-impl Solution {
-    pub fn max_depth(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
-        if root.is_none(){
-            return 0;
-        }
-        let mut max_depth: i32 = 0;
-        let mut stack = vec![root.unwrap()];
-        while !stack.is_empty() {
-            let num = stack.len();
-            for _i in 0..num{
-                let top = stack.remove(0);
-                if top.borrow_mut().left.is_some(){
-                    stack.push(top.borrow_mut().left.take().unwrap());
-                }
-                if top.borrow_mut().right.is_some(){
-                    stack.push(top.borrow_mut().right.take().unwrap());
-                }
-            }
-            max_depth+=1;
-        }
-        max_depth
-    }
-```
-
 
 那么我们可以顺便解决一下n叉树的最大深度问题
 
@@ -975,6 +949,50 @@ object Solution {
 }
 ```
 
+## rust
+### 0104.二叉树的最大深度
+
+递归：
+```rust
+impl Solution {
+    pub fn max_depth(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
+        if root.is_none() {
+            return 0;
+        }
+        std::cmp::max(
+            Self::max_depth(root.clone().unwrap().borrow().left.clone()),
+            Self::max_depth(root.unwrap().borrow().right.clone()),
+        ) + 1
+    }
+}
+```
+
+迭代：
+```rust
+impl Solution {
+    pub fn max_depth(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
+        if root.is_none(){
+            return 0;
+        }
+        let mut max_depth: i32 = 0;
+        let mut stack = vec![root.unwrap()];
+        while !stack.is_empty() {
+            let num = stack.len();
+            for _i in 0..num{
+                let top = stack.remove(0);
+                if top.borrow_mut().left.is_some(){
+                    stack.push(top.borrow_mut().left.take().unwrap());
+                }
+                if top.borrow_mut().right.is_some(){
+                    stack.push(top.borrow_mut().right.take().unwrap());
+                }
+            }
+            max_depth+=1;
+        }
+        max_depth
+    }
+```
+
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