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  • [Leetcode] Convert Sorted Array to Binary Search Tree

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

    哎,又是被指针坑了,指针作为函数的参数传递时,在函数体内可以修改指针所指的内容,但是不有修改指针本身,所以一时是运行时错误,这里要用指针的引用TreeNode *&,问题得解。算法没什么好说的,递归求解,每次取传入列表的中位数为节点的值。

     1 /**
     2  * Definition for binary tree
     3  * struct TreeNode {
     4  *     int val;
     5  *     TreeNode *left;
     6  *     TreeNode *right;
     7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
     8  * };
     9  */
    10 class Solution {
    11 public:
    12     void buildTree(TreeNode *&root, vector<int> &num, int l, int h) {
    13         if (l <= h) {
    14             int mid = (l + h) / 2;
    15             root = new TreeNode(num[mid]);
    16             buildTree(root->left, num, l, mid - 1);
    17             buildTree(root->right, num, mid + 1, h);
    18         }
    19     }
    20     
    21     TreeNode *sortedArrayToBST(vector<int> &num) {
    22         if (num.size() < 1) {
    23             return NULL;
    24         }
    25         TreeNode *root;
    26         buildTree(root, num, 0, num.size() - 1);
    27         return root;
    28     }
    29 };
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  • 原文地址:https://www.cnblogs.com/easonliu/p/3644300.html
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