// [3,9,20,null,null,15,7] 3
// [1,null,2] 2
use std::rc::Rc;
use std::cell::RefCell;
// 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,
}
}
}
// 递归
pub fn max_depth(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
fn dfs(node: &Option<Rc<RefCell<TreeNode>>>) -> i32 {
if let Some(node) = node {
let left_depth = dfs(&node.borrow().left);
let right_depth = dfs(&node.borrow().right);
return 1 + left_depth.max(right_depth);
}
0
}
dfs(&root)
}
use std::collections::VecDeque;
// 迭代
pub fn max_depth2(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
if root.is_none() {
return 0;
}
let mut queue = VecDeque::new();
queue.push_back(root);
let mut depth = 0;
while !queue.is_empty() {
let level_size = queue.len();
for _ in 0..level_size {
if let Some(Some(node)) = queue.pop_front() {
let node = node.borrow();
if let Some(left) = node.left.clone() {
queue.push_back(Some(left));
}
if let Some(right) = node.right.clone() {
queue.push_back(Some(right));
}
}
}
depth += 1;
}
depth
}
fn main() {
// 根据 [3,9,20,null,null,15,7] 3 编写测试用例
let root = Some(Rc::new(RefCell::new(TreeNode {
val: 3,
left: Some(Rc::new(RefCell::new(TreeNode::new(9)))),
right: Some(Rc::new(RefCell::new(TreeNode {
val: 20,
left: Some(Rc::new(RefCell::new(TreeNode::new(15)))),
right: Some(Rc::new(RefCell::new(TreeNode::new(7)))),
}))),
})));
assert_eq!(max_depth(root.clone()), 3);
assert_eq!(max_depth2(root.clone()), 3);
}
标签:node,right,N.104,Some,let,二叉树,new,leetcode,left
From: https://blog.csdn.net/BECOMEviolet/article/details/140364812