We are given the root
node of a maximum tree: a tree where every node has a value greater than any other value in its subtree.
Just as in the previous problem, the given tree was constructed from an list A
(root = Construct(A)
) recursively with the following Construct(A)
routine:
A
is empty, return null
.A[i]
be the largest element of A
. Create a root
node with value A[i]
.root
will be Construct([A[0], A[1], ..., A[i-1]])
root
will be Construct([A[i+1], A[i+2], ..., A[A.length - 1]])
root
.Note that we were not given A directly, only a root node root = Construct(A)
.
Suppose B
is a copy of A
with the value val
appended to it. It is guaranteed that B
has unique values.
Return Construct(B)
.
Example 1:
Input: root = [4,1,3,null,null,2], val = 5 Output: [5,4,null,1,3,null,null,2] Explanation: A = [1,4,2,3], B = [1,4,2,3,5]
Example 2:
Input: root = [5,2,4,null,1], val = 3 Output: [5,2,4,null,1,null,3] Explanation: A = [2,1,5,4], B = [2,1,5,4,3]
Example 3:
Input: root = [5,2,3,null,1], val = 4 Output: [5,2,4,null,1,3] Explanation: A = [2,1,5,3], B = [2,1,5,3,4]
Constraints:
1 <= B.length <= 100
struct Solution;
use rustgym_util::*;
trait Postorder {
fn insert(self, val: i32) -> Self;
}
impl Postorder for TreeLink {
fn insert(self, val: i32) -> Self {
if let Some(node) = self {
let node_val = node.borrow().val;
if node_val < val {
tree!(val, Some(node), None)
} else {
let right = node.borrow_mut().right.take();
node.borrow_mut().right = right.insert(val);
Some(node)
}
} else {
tree!(val)
}
}
}
impl Solution {
fn insert_into_max_tree(root: TreeLink, val: i32) -> TreeLink {
root.insert(val)
}
}
#[test]
fn test() {
let root = tree!(4, tree!(1), tree!(3, tree!(2), None));
let val = 5;
let res = tree!(5, tree!(4, tree!(1), tree!(3, tree!(2), None)), None);
assert_eq!(Solution::insert_into_max_tree(root, val), res);
let root = tree!(5, tree!(2, None, tree!(1)), tree!(4));
let val = 3;
let res = tree!(5, tree!(2, None, tree!(1)), tree!(4, None, tree!(3)));
assert_eq!(Solution::insert_into_max_tree(root, val), res);
let root = tree!(5, tree!(2, None, tree!(1)), tree!(3));
let val = 4;
let res = tree!(5, tree!(2, None, tree!(1)), tree!(4, tree!(3), None));
assert_eq!(Solution::insert_into_max_tree(root, val), res);
}