993. Cousins in Binary Tree

In a binary tree, the root node is at depth `0`, and children of each depth `k` node are at depth `k+1`.

Two nodes of a binary tree are cousins if they have the same depth, but have different parents.

We are given the `root` of a binary tree with unique values, and the values `x` and `y` of two different nodes in the tree.

Return `true` if and only if the nodes corresponding to the values `x` and `y` are cousins.

Example 1:

```Input: root = [1,2,3,4], x = 4, y = 3
Output: false
```

Example 2:

```Input: root = [1,2,3,null,4,null,5], x = 5, y = 4
Output: true
```

Example 3:

```Input: root = [1,2,3,null,4], x = 2, y = 3
Output: false
```

Constraints:

• The number of nodes in the tree will be between `2` and `100`.
• Each node has a unique integer value from `1` to `100`.

993. Cousins in Binary Tree
``````struct Solution;
use rustgym_util::*;

trait Preorder {
fn preorder(&self, depth: usize, parent: i32, res: &mut Option<(usize, i32)>, v: i32);
}

impl Preorder for TreeLink {
fn preorder(&self, depth: usize, parent: i32, res: &mut Option<(usize, i32)>, v: i32) {
if res.is_some() {
return;
}
if let Some(node) = self {
let node = node.borrow();
let val = node.val;
if v == val {
*res = Some((depth, parent));
}
node.left.preorder(depth + 1, val, res, v);
node.right.preorder(depth + 1, val, res, v);
}
}
}

impl Solution {
fn is_cousins(root: TreeLink, x: i32, y: i32) -> bool {
let mut rx: Option<(usize, i32)> = None;
let mut ry: Option<(usize, i32)> = None;
root.preorder(0, 0, &mut rx, x);
root.preorder(0, 0, &mut ry, y);
if let (Some((dx, px)), Some((dy, py))) = (rx, ry) {
dx == dy && px != py
} else {
false
}
}
}

#[test]
fn test() {
let root = tree!(1, tree!(2, tree!(4), None), tree!(3));
let x = 4;
let y = 3;
let res = false;
assert_eq!(Solution::is_cousins(root, x, y), res);
let root = tree!(1, tree!(2, None, tree!(4)), tree!(3, None, tree!(5)));
let x = 5;
let y = 4;
let res = true;
assert_eq!(Solution::is_cousins(root, x, y), res);
let root = tree!(1, tree!(2, None, tree!(4)), tree!(3));
let x = 2;
let y = 3;
let res = false;
assert_eq!(Solution::is_cousins(root, x, y), res);
}
``````