654. Maximum Binary Tree

简单的数的递归

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    int findmax(vector<int>& nums, int left, int right)    {        int maxIndex = -1000;        int maxValue = -1000;        for(int i=left;i<=right;i++)        {            if(nums[i]>maxValue)            {                maxValue = nums[i];                maxIndex = i;            }        }        return maxIndex;    }    TreeNode* buildTree(vector<int>& nums, int left, int right) {        if(left>right)            return NULL;        int splitIndex = findmax(nums, left, right);        //cout<<left<<" "<<right<<" "<<splitIndex<<endl;        TreeNode* root = new TreeNode(0);        root->val = nums[splitIndex];        root->left = buildTree(nums, left, splitIndex-1);        root->right = buildTree(nums, splitIndex+1, right);        return root;    }    TreeNode* constructMaximumBinaryTree(vector<int>& nums) {        return buildTree(nums,0, nums.size()-1);    }};