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面试题 04.02. 最小高度树

Posted on Edited on In Disqus:
Symbols count in article: 611 Reading time ≈ 1 mins.

面试题 04.02. 最小高度树

逆向inorder-traversal

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/**
 * 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) {
        return helper(nums, 0, nums.size() - 1);
    }
private:
    TreeNode* helper(vector<int>& nums, int lo, int hi)
    {
        if(lo > hi)
            return nullptr;
        int mid = lo + (hi - lo) / 2;
        TreeNode* root = new TreeNode(nums[mid]);
        root->left = helper(nums, lo, mid - 1);
        root->right = helper(nums, mid + 1, hi);
        return root;
    }
};