LeetCode题解Maximum Binary Tree

1、题目描述

2、分析

找出最大元素，然后分割数组调用。

3、代码

 TreeNode* constructMaximumBinaryTree(vector<int>& nums) {
        int size = nums.size();
        if (size == 0)
            return NULL;
        TreeNode *dummy = new TreeNode(0);
        maxcont(dummy->left, 0, size-1, nums);
        return dummy->left;
    }
    
    void maxcont(TreeNode* &parent, int left, int right, vector<int>& nums)
    {
        if (left > right )
            return ;
        int maxindex = find_max(left, right, nums);
        TreeNode *tmp = new TreeNode(nums[maxindex]);
        parent = tmp;
        maxcont(tmp->left, left, maxindex-1, nums);
        maxcont(tmp->right, maxindex + 1, right, nums);
    }
    
    int find_max(int left, int right, vector<int> &nums)
    {
        int n = 0;
        int maxVal = INT_MIN;
        for (int i = left; i <= right ; i++) {
            if ( nums[i] > maxVal) {
                maxVal = nums[i];
                n = i;
            }
                
        }
        return n;
    }