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101.symmetric-tree.rs
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101.symmetric-tree.rs
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/*
* @lc app=leetcode id=101 lang=rust
*
* [101] Symmetric Tree
*/
// @lc code=start
// 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 is_symmetric(root: Option<Rc<RefCell<TreeNode>>>) -> bool {
if root.is_none() { return true; }
let mut nodes = vec![root];
while true {
let mut tmp = vec![];
let mut has_some = false;
for node in nodes {
if let Some(rc_node) = node {
let tree_node = rc_node.borrow();
tmp.push(tree_node.left.clone());
tmp.push(tree_node.right.clone());
has_some = true;
} else {
tmp.push(None);
tmp.push(None);
}
}
if !has_some { break; }
let N = tmp.len();
if N % 2 != 0 {
return false;
}
for i in 0..N/2 {
let is_sym = match (tmp[i].clone(), tmp[N-i-1].clone()) {
(Some(left), Some(right)) => {
left.borrow().val == right.borrow().val
},
(None, None) => true,
_ => false
};
if !is_sym { return false; }
}
nodes = tmp;
}
return true;
}
}
// @lc code=end