q199

Author: OhBonsai

src/tree/mod.rs

@@ -136,4 +136,5 @@ macro_rules! tree {
 mod q108;
 mod q95;
 mod q129;
-mod q1382;
+mod q1382;
+mod q199;

src/tree/q199.rs

@@ -0,0 +1,68 @@
+/// Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.
+///
+/// Example:
+///
+/// Input: [1,2,3,null,5,null,4]
+/// Output: [1, 3, 4]
+/// Explanation:
+///
+/// 1            <---
+/// /   \
+/// 2     3         <---
+/// \     \
+/// 5     4       <---
+///
+/// 来源：力扣（LeetCode）
+/// 链接：https://leetcode-cn.com/problems/binary-tree-right-side-view
+/// 著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
+use super::*;
+use std::collections::VecDeque;
+
+struct Solution ();
+impl Solution {
+    pub fn right_side_view(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<i32> {
+
+        let mut result  = vec![];
+        let mut queue = VecDeque::new();
+
+        if root.is_some() {
+            queue.push_front((root.unwrap(), 1))
+        }
+
+        let mut last_lvl = 0;
+
+        while !queue.is_empty() {
+            let (r, lvl) = queue.pop_back().unwrap();
+
+
+            let rr = RefCell::borrow(&r);
+
+            if lvl != last_lvl {
+                last_lvl = lvl;
+                result.push(rr.val);
+            }
+            if let Some(r) = &rr.right {
+                queue.push_front((Rc::clone(r), lvl + 1))
+            }
+            if let Some(l) = &rr.left {
+                queue.push_front((Rc::clone(l), lvl + 1))
+            }
+        }
+        result
+
+    }
+
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1() {
+        let t =  tree!(1,2,3,null,5,null,4);
+        println!("{:?}", Solution::right_side_view(t));
+    }
+
+}