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
and100
. - Each node has a unique integer value from
1
to100
.
Rust Solution
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);
}
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