998. Maximum Binary Tree II

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:

• If `A` is empty, return `null`.
• Otherwise, let `A[i]` be the largest element of `A`.  Create a `root` node with value `A[i]`.
• The left child of `root` will be `Construct([A[0], A[1], ..., A[i-1]])`
• The right child of `root` will be `Construct([A[i+1], A[i+2], ..., A[A.length - 1]])`
• Return `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`

998. Maximum Binary Tree II
``````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);
}
``````