Binary tree right side view

Tree Depth-First Search Breadth-First Search Binary Tree

69.6% acceptance

Feb 27, 2026

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1086

Given the root of 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.

Solution

Rust

Time O(n²)

Space O(n)

LeetCode

solution.rs

// 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 right_side_view(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<i32> {
    let mut result = Vec::new();
    let mut queue = std::collections::VecDeque::new();
    
    if let Some(node) = root {
      queue.push_back(node);
    }
    
    while !queue.is_empty() {
      let level_size = queue.len();
      for i in 0..level_size {
        if let Some(node) = queue.pop_front() {
          let node = node.borrow();
          if i == level_size - 1 {
            result.push(node.val);
          }
          if let Some(left) = node.left.clone() {
            queue.push_back(left);
          }
          if let Some(right) = node.right.clone() {
            queue.push_back(right);
          }
        }
      }
    }
    
    result
  }
}