20240211 Finished

src/problem/mod.rs

@@ -44,3 +44,4 @@ mod p2641_cousins_in_binary_tree_ii;
 mod p993_cousins_in_binary_tree;
 mod p236_lowest_common_ancestor_of_a_binary_tree;
 mod p94_binary_tree_inorder_traversal;
+mod p144_binary_tree_preorder_traversal;

src/problem/p144_binary_tree_preorder_traversal.rs

@@ -0,0 +1,62 @@
+/**
+ * [144] Binary Tree Preorder Traversal
+ */
+pub struct Solution {}
+
+use crate::util::tree::{TreeNode, to_tree};
+
+// submission codes start here
+
+// 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
+//     }
+//   }
+// }
+use std::rc::Rc;
+use std::cell::RefCell;
+impl Solution {
+    pub fn preorder_traversal(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<i32> {
+        let mut result = Vec::new();
+        let mut stack = Vec::new();
+        let mut root = root;
+
+        while root.is_some() || !stack.is_empty() {
+            while let Some(r) = root {
+                result.push(r.borrow().val);
+                stack.push(Rc::clone(&r));
+                root = r.borrow().left.clone();
+            }
+
+            let node = stack.pop().unwrap();
+            root = node.borrow().right.clone();
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_144() {
+        assert_eq!(Solution::preorder_traversal(to_tree(
+            vec![Some(1), None, Some(2), Some(3)])), vec![1,2,3]);
+    }
+}