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:
    int create(vector a){
        if(a.size()==0)return -1;
        int m=a[0],mindex=0;
        for(int i=1;im){
                    m=a[i];
                    mindex=i;
                }
        }
        return mindex;
    }
    TreeNode* constructMaximumBinaryTree(vector& nums) {
        if(nums.size()==0)return NULL;
        int k=create(nums);
        TreeNode *root=new  TreeNode;
        root->val=nums[k];
        vectorlefttree(nums.begin(),nums.begin()+k);
        vectorrighttree(nums.begin()+k+1,nums.end());
        root->left=constructMaximumBinaryTree(lefttree);
        root->right=constructMaximumBinaryTree(righttree);
        return root;
    }
};