Function leetcode_for_rust::cd0104_maximum_depth_of_binary_tree::max_depth

pub fn max_depth(root: Option<Rc<RefCell<TreeNode>>>) -> i32

Solutions

Approach 1: DFS

• Time complexity: O(n)

• Space complexity: O(1)

• Runtime: 4 ms

• Memory: 3.1 MB

// 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;
use std::cmp::Ord;
impl Solution {
    pub fn max_depth(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
        match root {
            Some(node) => {
                let left = Self::max_depth(node.borrow().left.clone());
                let right = Self::max_depth(node.borrow().right.clone());

                1 + left.max(right)
            },
            _ => 0,
        }
    }
}

Approach 2: BFS

• Time complexity: O(n)

• Space complexity: O(1)

• Runtime: 0 ms

• Memory: 3.2 MB

// 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;
use std::collections::VecDeque;
impl Solution {
    pub fn max_depth(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
        if root.is_none() { return 0; }

        let mut depth = 0;
        let mut deque: VecDeque<Option<Rc<RefCell<TreeNode>>>> = VecDeque::new();
        deque.push_back(root);

        while !deque.is_empty() {
            let level_size = deque.len();
            let mut added = false;
            depth += 1;
            for _i in 0..level_size {
                let n = deque.pop_front();
                added = true;
                if let Some(Some(node)) = n {
                    if node.borrow().left.is_some() { deque.push_back(node.borrow().left.clone());}
                    if node.borrow().right.is_some() { deque.push_back(node.borrow().right.clone());}
                }
            }
            if !added { break; }
        }
        depth
    }
}