day20 - 二叉树 part06

654. 最大二叉树

详解

/**
 * 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* search(vector<int>& nums, int left, int right){
        if(left >= right) return nullptr;
        int index = left;
        for(int i=left+1; i<right; i++)
            if(nums[i] > nums[index])
                index = i;
        
        TreeNode* root = new TreeNode(nums[index]);
        root->left = search(nums, left, index);
        root->right = search(nums, index+1, right);

        return root;
    }

    TreeNode* constructMaximumBinaryTree(vector<int>& nums) {
        return search(nums, 0, nums.size());
    }
};