rust leetcode 107

rust-leetcode/README.md

@@ -17,6 +17,7 @@ Leetcode Rust 实现
 * [面试题 32 - II. 从上到下打印二叉树 II](src/interview_32_2.rs)
 * [100 相同的树](src/leetcode_100.rs)
 * [101 对称二叉树](src/leetcode_101.rs)
+* [107 二叉树的层次遍历 II](src/leetcode_107.rs)
 
 ## 链表&栈&队列
 

rust-leetcode/src/leetcode_107.rs

+use std::borrow::Borrow;
+use std::cell::RefCell;
+use std::collections::VecDeque;
+use std::rc::Rc;
+
+use crate::pre_structs::{Solution, TreeNode};
+
+/// 107. 二叉树的层次遍历 II
+/// 给定一个二叉树，返回其节点值自底向上的层次遍历。 （即按从叶子节点所在层到根节点所在的层，逐层从左向右遍历）
+/// 例如：
+/// 给定二叉树 [3,9,20,null,null,15,7],
+impl Solution {
+    pub fn level_order_bottom(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<Vec<i32>> {
+        let mut ret = Vec::new();
+        let mut node_level = VecDeque::new();
+        let mut level = Vec::new();
+        let mut flag = root.clone();
+        node_level.push_back(root.clone());
+        while !node_level.is_empty() {
+            let curr_node = node_level.pop_front();
+            if let Some(node) = curr_node {
+                if let Some(n) = node {
+                    level.push(n.try_borrow().unwrap().val);
+                    if n.try_borrow().unwrap().left.is_some() {
+                        node_level.push_back(n.try_borrow().unwrap().left.clone());
+                    }
+                    if n.try_borrow().unwrap().right.is_some() {
+                        node_level.push_back(n.try_borrow().unwrap().right.clone());
+                    }
+                    if let Some(f) = flag.borrow() {
+                        if f.as_ptr() == n.as_ptr() {
+                            //直接back导致as_ptr不等
+                            let tail = node_level.pop_back();
+                            if tail.is_some() {
+                                flag = tail.clone().unwrap();
+                                node_level.push_back(tail.unwrap());
+                            }
+                            ret.insert(0, level);
+                            level = Vec::new();
+                        }
+                    }
+                }
+            }
+        }
+        ret
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use std::cell::RefCell;
+    use std::rc::Rc;
+
+    use crate::pre_structs::{ListNode, Solution, TreeNode};
+
+    #[test]
+    fn level_order_bottom() {
+        let e7 = Some(Rc::new(RefCell::new(TreeNode {
+            val: 7,
+            left: None,
+            right: None,
+        })));
+        let e15 = Some(Rc::new(RefCell::new(TreeNode {
+            val: 15,
+            left: None,
+            right: None,
+        })));
+        let e20 = Some(Rc::new(RefCell::new(TreeNode {
+            val: 20,
+            left: e15,
+            right: e7,
+        })));
+        let e9 = Some(Rc::new(RefCell::new(TreeNode {
+            val: 9,
+            left: None,
+            right: None,
+        })));
+        let e3 = Some(Rc::new(RefCell::new(TreeNode {
+            val: 3,
+            left: e9,
+            right: e20,
+        })));
+        let ret = Solution::level_order_bottom(e3);
+        assert!(ret.len() == 3 && ret[0].len() == 2);
+    }
+}

rust-leetcode/src/main.rs

@@ -23,6 +23,7 @@ pub mod leetcode_100;
 pub mod leetcode_101;
 pub mod leetcode_1021;
 pub mod leetcode_1051;
+pub mod leetcode_107;
 pub mod leetcode_108;
 pub mod leetcode_1160;
 pub mod leetcode_1207;