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我正在尝试实现链接的插入功能，但是一旦添加第三个元素，程序就会崩溃并停止执行，即使相同的代码在hackerrank的编译器上工作。

这是我的代码。

#include<bits/stdc++.h>
using namespace std;

class Node{
    public:
        int data;
        Node * next;
        Node(int data){
            this -> data = data;
            this -> next = nullptr;
        }
};

Node * insert_tail(Node * head, int data){
    Node * node = new Node(data);
    if(head == nullptr) return node;
    Node * current = head;
    while(head -> next != nullptr) current = current -> next;
    current -> next = node;
    return head;
}

void print_linkedlist(Node * head){
    while(head -> next != nullptr){
        cout << head -> data << " -> ";
        head = head -> next;
    }
    cout << head -> data << " -> nullptr";
}

int main(){
    Node *  head = nullptr;
    head = insert_tail(head, 1);
    head = insert_tail(head, 5);
    head = insert_tail(head, 3);
    head = insert_tail(head, 5);
    head = insert_tail(head, 8);
    head = insert_tail(head, 17);

    print_linkedlist(head);
    return 0;
}
4

2 回答 2

1

线

    while(head -> next != nullptr) current = current -> next;

在函数insert_tail中是错误的。head->next不在时它会无休止地运行nullptr。

它应该是

    while(current -> next != nullptr) current = current -> next;
于 2020-10-28T19:29:24.617 回答
1

这是一个错字

while(head -> next != nullptr) current = current -> next;
      ^^^^^^^^^^^^

写

while(current -> next != nullptr) current = current -> next;
      ^^^^^^^^^^^^

函数的另一种定义可以如下所示，

void insert_tail( Node * &head, int data )
{
    Node **current = &head;

    while ( *current ) current = &( *current )->next;

    *current = new Node( data );
}

并且可以简单地调用该函数

insert_tail(head, 1);

该函数print_linkedlist也可以写成

std::ostream & print_linkedlist( const Node * head, std::ostream &os = std::cout )
{
    for ( ; head; head = head->next )
    {
        os << head -> data << " -> ";
    }

    return os << "nullptr";
}

并且可以称为

print_linkedlist(head) << '\n';
于 2020-10-28T19:30:07.290 回答