问题4.9 Ctci的C ++代码（破解inteview编码第6版）不起作用？

Question

  

问题：

     

4.9 BST序列：通过从左到右遍历数组来创建二进制搜索树   并插入每个元素。给定具有不同元素的二叉搜索树，请打印所有可能的   可能导致这棵树的数组。

示例：对于给定的树：                                   

我尝试按照书中的说明使用c ++编写给定的解决方案，但在运行时崩溃。

  

未能找到错误，但我认为这与c ++中的reference＆有关系。

下面是我的代码：

#include <iostream>
#include<vector>
#include<list>
using namespace std;
class TreeNode{
    public:
    int val;
    TreeNode* left;
    TreeNode* right;
    TreeNode(int v){
        val = v; left = nullptr; right = nullptr;
    }
};
void weave(vector<list<int>> &, list<int> &, list<int> &, list<int> &);
vector<list<int>>& allSequence(TreeNode *);

vector<list<int>>& allSequence(TreeNode *root){

    vector<list<int>> result_seq;

    if(!root){
        result_seq.push_back(list<int>());
        return result_seq;
    }

    list<int> prefix ;
    prefix.push_back(root->val);

    vector<list<int>> &leftSeq =  allSequence(root->left);
    vector<list<int>> &rightSeq = allSequence(root->right);



    for(int i = 0; i < leftSeq.size(); i++){

        for(int j = 0; j < rightSeq.size(); j++){
            vector<list<int>> weaved;
            weave(weaved, leftSeq[i], rightSeq[j], prefix);

            result_seq.insert(result_seq.end(), weaved.begin(), weaved.end());
        }
    }

    return result_seq;
}

/** Weave lists together in all possible ways. This algorithm works by removing the
 head from one list, recursing, and then doing the same thing with the other
 list. */

void weave(vector<list<int>> &results, list<int> &first, list<int> &second, list<int> &prefix){
    /** One list is empty. Add remainder to [a cloned] prefix and store result. */


    if(first.size() == 0 || second.size() == 0){

        list<int> result(prefix.begin(), prefix.end());
        (first.size()) ? (result.insert(result.end(), first.begin(), first.end())) : (result.insert(result.end(), second.begin(), second.end()));

        results.push_back(result);

        return;
    }

    int headFirst = first.front(); first.pop_front();
    prefix.push_back(headFirst);
    weave(results, first, second, prefix);
    prefix.pop_back();
    first.push_front(headFirst);

    int headSecond = second.front(); second.pop_front();
    prefix.push_back(headSecond);
    weave(results, first, second, prefix);
    prefix.pop_back();
    second.push_front(headSecond);
}

int main() {
TreeNode *root = new TreeNode(5);
    root->right = new TreeNode(7);
    root->left = new TreeNode(3);

    vector<list<int>> allSequence_As_list = allSequence(root)

    /// print
    for(auto i = allSequence_As_list.begin(); i != allSequence_As_list.end(); i++){
        for(auto j = (*i).begin(); j!= (*i).end(); j++)
            cout<<*j<<" ";
        cout<<"\n";
    }

}