998. Maximum Binary Tree II

Problem

A maximum tree is a tree where every node has a value greater than any other value in its subtree.

You are given the root of a maximum binary tree and an integer val.

Just as in the previous problem, the given tree was constructed from a 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 the 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:

• The number of nodes in the tree is in the range [1, 100].

• 1 <= Node.val <= 100

• All the values of the tree are unique.

• 1 <= val <= 100

Solution

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @param {number} val
 * @return {TreeNode}
 */
var insertIntoMaxTree = function(root, val) {
    var nodes = [];
    var now = root;
    while (now) {
        nodes.push(now);
        now = now.right;
    }
    for (var i = nodes.length - 1; i >= 0; i--) {
        if (nodes[i].val < val) continue;
        nodes[i].right = new TreeNode(val, nodes[i].right);
        return root;
    }
    return new TreeNode(val, root);
};

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).