我正在进行字符串链接列表的分配。在我到达分拣部分之前，一切似乎都能正常工作。我也在上课。我已经有2个功能。第一个minimum(string)，它返回按字母顺序排在第一位的字符串。
此功能正常。我还有一个函数remove(string)，它从链表中删除包含给定字符串的节点。如果成功则返回true，否则返回false（如果字符串不在列表中），在这种情况下我必须擦除minimum(string)函数返回的字符串。我遇到问题的功能是sort()。
它要我定义一个StringNode指针作为新列表的头部（空列表）然后我需要一个循环，我将调用minimum(string)和{{1}的函数}。在循环内部，我还需要将此节点插入新列表中的正确位置（将其附加到末尾）。旧的头指针（现在为空）必须指向新列表。
我对此非常困惑，到目前为止我有这个：
remove(string)我的理解是：我需要创建一个新的节点，它将是一个空列表，意思是void StringList::sort()
{
StringNode *newList = new StringNode;
newList = NULL;
string mini;
bool removed;
while (newList->next != NULL)
{
StringNode *newList2 = new StringNode;
StringNode *p = head;
mini = minimum();
p->data = mini;
p->next = NULL;
newList2 = newList2->next;
newList2->next = p;
removed = remove(mini);
newList = newList2;
}
}
然后在循环中我需要创建另一个新节点，以及一个指向新头部的指针循环内的节点。我需要将最小值给出的值存储在指针newList->next = NULL;中，指针指向新节点。
任何帮助将不胜感激。谢谢！
这是洞程序。
// StringList.cpp
p// StringList.h
#include <iomanip>
#include <iostream>
#include <sstream>
#include "StringList.h"
using namespace std;
//******************************************************************************
// StringList: creates an empty list
//******************************************************************************
StringList::StringList()
{
head = NULL;
}
//******************************************************************************
// StringList: deallocates all the nodes in StringList
//******************************************************************************
StringList::~StringList()
{
StringNode *p;
StringNode *n;
p = head;
while (p != NULL)
{
n = p->next;
delete p;
p = n;
}
}
//******************************************************************************
// count: returns the total number of nodes in the list.
//******************************************************************************
int StringList::count()
{
int count = 0;
StringNode *p;
p = head;
while ( p != NULL )
{
count++;
p = p->next;
}
return count;
}
//******************************************************************************
// add: adds a new node to the beginning of the list.
//******************************************************************************
void StringList::add(string movie)
{
StringNode *newNode = new StringNode;
newNode->data = movie;
newNode->next = head;
head = newNode;
}
//******************************************************************************
// remove: removes a node containing the string from linked list
// returns true if successful or false the string is not in the list
//******************************************************************************
bool StringList::remove(string movie)
{
StringNode *p = head;
StringNode *n = NULL;
while (p != NULL && p->data != movie )
{
n = p;
p = p->next;
if (p == NULL )
{
return false;
}
else if (p->data == movie)
{
n->next = p->next;
delete p;
return true;
}
}
}
//******************************************************************************
//display: Displays the strings in the list.
//******************************************************************************
void StringList::display()
{
StringNode *p;
p = head;
while (p != NULL)
{
cout << p->data << " ";
p = p->next;
}
cout << endl;
}
//******************************************************************************
//minimum: return the string in alphabetical order
//******************************************************************************
string StringList::minimum()
{
StringNode *p = head;
string minimum = p->data;
while (p->next != NULL)
{
p = p->next;
if(minimum > p->data)
{
minimum = p->data;
}
}
return minimum;
}
//******************************************************************************
//sort: will call the minimum function and remove function
//******************************************************************************
void StringList::sort()
{
StringNode* newhead; // create a new head pointer
string mini;
bool removed;
//adding the first node to the new list.
StringNode *newnode = new StringNode;
mini = minimum(); // get the minimum from the existing linked list
newnode->data = mini;
newnode->next = NULL;
newhead=newnode; //add the minimum node to the new list(with the newhead)
StringNode *p = newhead;
while (head != NULL) // loop should run until there's no node left in the original list
{
StringNode *newnode = new StringNode;
mini = minimum(); // get the minimum from the existing linked list
newnode->data = mini;
newnode->next = NULL;
p->next=newnode; //add the minimum node to the new list(with the newhead pointer)
removed = remove(mini);
p=p->next;
}
head=newhead; //finally change the head pointer, so that the head now points to sorted list.
}
// Driver.cpp
#ifndef STRINGLIST_H_INCLUDED
#define STRINGLIST_H_INCLUDED
#include <string>
using namespace std;
class StringList
{
private:
struct StringNode // the Nodes of the linked list
{
string data; // data is a string
StringNode *next; // points to next node in list
};
StringNode *head; // the head pointer
public:
StringList();
~StringList();
int count();
void add(string);
bool remove(string);
void display();
string minimum();
void sort();
};
#endif // STRINGLIST_H_INCLUDED
答案 0 :(得分：1)
你的删除功能有小故障。您没有注意删除第一个节点的可能性。
bool StringList::remove(string movie)
{
StringNode *p = head;
StringNode *n = NULL;
if(p->data==movie) //added this condition
{
head=head->next;
delete p;
return true;
}
while (p != NULL && p->data != movie )
{
n = p;
p = p->next;
if (p == NULL )
{
return false;
}
else if (p->data == movie)
{
n->next = p->next;
delete p;
return true;
}
}
}
最终排序功能。目标是使用minimum和remove函数对现有列表进行排序，并获取新的排序列表。您需要从现有列表中获得最小值，并将其添加到新列表的末尾。最后更改头指针以将其指向新列表。
while循环应该运行，直到现有列表变空。
void StringList::sort()
{
string mini;
bool removed;
//adding the first node to the new list.
StringNode *newnode1 = new StringNode;
mini = minimum(); // get the minimum from the existing linked list
newnode1->data = mini;
newnode1->next = NULL;
removed =remove(mini);
StringNode *p = newnode1;
while (head != NULL) // the loop should run until the original list is empty
{
StringNode *newnode = new StringNode;
mini = minimum(); // get the minimum from the existing linked list
newnode->data = mini;
newnode->next = NULL;
p->next=newnode; //add the minimum node to the new list
removed = remove(mini);
p=p->next;
}
head=newnode1; //finally change the head pointer, so that the head now points to sorted list.
}