【2019秋冬】【LeetCode】108 将有序數組轉換為二叉搜尋樹

/**
 * 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:
    TreeNode* sortedArrayToBST(vector<int>& nums) {  
        if(nums.size()==0) return NULL;     
        int a = nums.size()-1;
        return half(nums,0,a);
    }
    TreeNode* half(vector<int>& nums,int l, int r){
        if(l>r) return NULL;
        int mid = (l+r)/2;
        TreeNode* tree = new TreeNode(nums[mid]);
        tree->left = half(nums,l,mid-1);
        tree->right = half(nums,mid+1,r);
        return tree;
    }
};
           

二分法

指針建樹