create 0543-diameter-of-binary-tree.rs

Author: rmrt1n

rust/0543-diameter-of-binary-tree.rs

@@ -0,0 +1,21 @@
+use std::rc::Rc;
+use std::cell::RefCell;
+impl Solution {
+    pub fn diameter_of_binary_tree(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
+        fn dfs(root: Option<Rc<RefCell<TreeNode>>>) -> (i32, i32) {
+            match root {
+                None => (0, 0),
+                Some(node) => {
+                    let (l_diameter, l_max) = dfs(node.borrow().left.clone());
+                    let (r_diameter, r_max) = dfs(node.borrow().right.clone());
+                    (
+                        1 + l_diameter.max(r_diameter),
+                        l_max.max(r_max.max(l_diameter + r_diameter)),
+                    )
+                }
+            }
+        }
+    
+        dfs(root).1
+    }
+}