subtree-of-another-tree

Author: DaleSeo

subtree-of-another-tree/DaleSeo.rs

@@ -0,0 +1,53 @@
+// Definition for a binary tree node.
+// #[derive(Debug, PartialEq, Eq)]
+// pub struct TreeNode {
+//   pub val: i32,
+//   pub left: Option<Rc<RefCell<TreeNode>>>,
+//   pub right: Option<Rc<RefCell<TreeNode>>>,
+// }
+//
+// impl TreeNode {
+//   #[inline]
+//   pub fn new(val: i32) -> Self {
+//     TreeNode {
+//       val,
+//       left: None,
+//       right: None
+//     }
+//   }
+// }
+
+// LC :O(r × s)
+// SC :O(r + s)
+use std::cell::RefCell;
+use std::rc::Rc;
+impl Solution {
+    pub fn is_subtree(
+        root: Option<Rc<RefCell<TreeNode>>>,
+        sub_root: Option<Rc<RefCell<TreeNode>>>,
+    ) -> bool {
+        fn is_same(a: &Option<Rc<RefCell<TreeNode>>>, b: &Option<Rc<RefCell<TreeNode>>>) -> bool {
+            match (a, b) {
+                (None, None) => true,
+                (Some(a), Some(b)) => {
+                    let a = a.borrow();
+                    let b = b.borrow();
+                    a.val == b.val && is_same(&a.left, &b.left) && is_same(&a.right, &b.right)
+                }
+                _ => false,
+            }
+        }
+
+        match &root {
+            None => sub_root.is_none(),
+            Some(node) => {
+                if is_same(&root, &sub_root) {
+                    return true;
+                }
+                let node = node.borrow();
+                Self::is_subtree(node.left.clone(), sub_root.clone())
+                    || Self::is_subtree(node.right.clone(), sub_root.clone())
+            }
+        }
+    }
+}