129. Sum Root to Leaf Numbers

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

Note: For the purpose of this problem, we define empty string as valid palindrome.

Example 1:

```Input: "A man, a plan, a canal: Panama"
Output: true
```

Example 2:

```Input: "race a car"
Output: false
```

Constraints:

• `s` consists only of printable ASCII characters.

129. Sum Root to Leaf Numbers
``````struct Solution;
use rustgym_util::*;

trait Preorder {
fn preorder(&self, path: i32, sum: &mut i32);
}

fn preorder(&self, path: i32, sum: &mut i32) {
if let Some(node) = self {
let node = node.borrow();
let val = node.val;
let path = path * 10 + val;
if node.left.is_none() && node.right.is_none() {
*sum += path;
}
node.left.preorder(path, sum);
node.right.preorder(path, sum);
}
}
}

impl Solution {
fn sum_numbers(root: TreeLink) -> i32 {
let mut res = 0;
root.preorder(0, &mut res);
res
}
}

#[test]
fn test() {
let root = tree!(1, tree!(2), tree!(3));
let res = 25;
assert_eq!(Solution::sum_numbers(root), res);
let root = tree!(4, tree!(9, tree!(5), tree!(1)), tree!(0));
let res = 1026;
assert_eq!(Solution::sum_numbers(root), res);
}
``````