998. Maximum Binary Tree II

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998. Maximum Binary Tree II

Description

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:

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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:

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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:

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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

Hints/Notes

  • N/A

Solution

Language: C++

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/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left),
 * right(right) {}
 * };
 */
class Solution {
public:
    TreeNode* insertIntoMaxTree(TreeNode* root, int val) {
        if (!root) {
            return new TreeNode(val);
        }
        if (root->val < val) {
            TreeNode* newRoot = new TreeNode(val);
            newRoot->left = root;
            return newRoot;
        } else {
            root->right = insertIntoMaxTree(root->right, val);
            return root;
        }
    }
};