[力扣题解] 654. 最大二叉树
/**
* 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* travel(vector<int>& nums, int start, int end)
{
// [start, end)
if(start == end)
{
return NULL;
}
int i, max = -1;
for(i = start; i < end; i++)
{
if(max < nums[i])
{
max = nums[i];
}
}
for(i = start; i < end; i++)
{
if(max == nums[i])
{
break;
}
}
TreeNode* root = new TreeNode(max);
// [start, i)
root->left = travel(nums, start, i);
// [i+1, start)
root->right = travel(nums, i+1, end);
return root;
}
TreeNode* constructMaximumBinaryTree(vector<int>& nums) {
// [0, nums.size())
return travel(nums, 0, nums.size());
}
};