Average of levels in binary tree

Tree Depth-First Search Breadth-First Search Binary Tree

74.7% acceptance

Feb 20, 2026

5556

352

Given the root of a binary tree, return the average value of the nodes on each level.

Solution

Rust

Time O(n²)

Space O(n)

LeetCode

solution.rs

use std::rc::Rc;
use std::cell::RefCell;
impl Solution {
  pub fn average_of_levels(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<f64> {
    let mut result = Vec::new();
    let mut queue = std::collections::VecDeque::new();
    if let Some(r) = root {
      queue.push_back(r);
    }
    while !queue.is_empty() {
      let level_size = queue.len();
      let mut sum = 0i64;
      for _ in 0..level_size {
        let node = queue.pop_front().unwrap();
        let b = node.borrow();
        sum += b.val as i64;
        if let Some(l) = b.left.clone() { queue.push_back(l); }
        if let Some(r) = b.right.clone() { queue.push_back(r); }
      }
      result.push(sum as f64 / level_size as f64);
    }
    result
  }
}