LeetCode--Convert Sorted List to Binary Search Tree

标签：leetcode   递归   bst   链表   

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution 
{
public:
    TreeNode *sortedListToBST(ListNode *head) 
    {
        if(head == NULL)
            return NULL;
        vector<int> res;
        ListNode* pre = head;
        while(pre!=NULL)
        {
            res.push_back(pre->val);
            pre = pre->next;
        }
        int n=res.size();
        return sortedArrayToBST(res,0,n-1); 
    }
    TreeNode *sortedArrayToBST(vector<int> &num, int low, int high) 
    {
        if(low>high)
            return NULL;
        if(low == high)
        {
            return new TreeNode(num[low]);
        }
        int mid = (low+high)/2;
        TreeNode* root = new TreeNode(num[mid]);
        root->left = sortedArrayToBST(num,low,mid-1);
        root->right = sortedArrayToBST(num,mid+1,high);
        return root;
    }
};

LeetCode--Convert Sorted List to Binary Search Tree

标签：leetcode   递归   bst   链表   

原文地址：http://blog.csdn.net/shaya118/article/details/42710239