feat: resolved

Author: jtr109

binary_tree_level_order_traveral/src/lib.rs

@@ -1,7 +1,55 @@
-#[cfg(test)]
-mod tests {
-    #[test]
-    fn it_works() {
-        assert_eq!(2 + 2, 4);
+/*!
+ * https://leetcode.com/explore/challenge/card/may-leetcoding-challenge-2021/600/week-3-may-15th-may-21st/3749/
+ */
+
+use std::cell::RefCell;
+use std::rc::Rc;
+
+// 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,
+        }
+    }
+}
+
+pub struct Solution {}
+
+impl Solution {
+    pub fn level_order(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<Vec<i32>> {
+        match root {
+            None => vec![],
+            Some(rt) => {
+                let mut left = Self::level_order(rt.borrow().left.clone());
+                let mut right = Self::level_order(rt.borrow().right.clone());
+                let mut result = vec![];
+                for i in 0..left.len().max(right.len()) + 1 {
+                    result.push(vec![]);
+                    if i == 0 {
+                        result[i].push(rt.borrow().val);
+                        continue;
+                    }
+                    let j = i - 1;
+                    if j < left.len() {
+                        result[i].append(&mut left[j]);
+                    }
+                    if j < right.len() {
+                        result[i].append(&mut right[j]);
+                    }
+                }
+                result
+            }
+        }
     }
 }