1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
use std::{cell::RefCell, rc::Rc};
pub struct Solution;
#[derive(Debug, PartialEq, Eq)]
pub struct TreeNode {
pub val: i32,
pub left: Option<Rc<RefCell<TreeNode>>>,
pub right: Option<Rc<RefCell<TreeNode>>>,
}
#[allow(unused)]
impl TreeNode {
#[inline]
pub fn new(val: i32) -> Self {
TreeNode { val, left: None, right: None }
}
}
#[allow(unused)]
impl Solution {
pub fn is_symmetric(root: Option<Rc<RefCell<TreeNode>>>) -> bool {
if root.is_none() {
return true
}
let root = root.unwrap();
let mut left = root.borrow().left.clone();
let mut right = root.borrow().right.clone();
Solution::is_symmetric_helper(&left, &right)
}
pub fn is_symmetric_helper(
left: &Option<Rc<RefCell<TreeNode>>>,
right: &Option<Rc<RefCell<TreeNode>>>,
) -> bool {
if left.is_none() && right.is_none() {
return true
}
if left.is_none() || right.is_none() {
return false
}
let left = left.as_ref().unwrap().borrow();
let right = right.as_ref().unwrap().borrow();
if left.val != right.val {
return false
}
Solution::is_symmetric_helper(&left.left, &right.right) &&
Solution::is_symmetric_helper(&left.right, &right.left)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
assert_eq!(Solution::is_symmetric(None), true);
assert_eq!(Solution::is_symmetric(Some(Rc::new(RefCell::new(TreeNode::new(1))))), true);
}
}