对于单链表的介绍部分参考自博文数组、单链表和双链表介绍 以及 双向链表的C/C++/Java实现。
1. 单链表介绍
单向链表(单链表)是链表的一种，它由节点组成，每个节点都包含下一个节点的指针。
1.1 单链表的示意图
表头为空，表头的后继节点是"节点10"(数据为10的节点)，"节点10"的后继节点是"节点20"(数据为10的节点)，...
1.2 单链表添加节点
在"节点10"与"节点20"之间添加"节点15"
添加之前："节点10" 的后继节点为"节点20"。
添加之后："节点10" 的后继节点为"节点15"，而"节点15" 的后继节点为"节点20"。
需要注意的是在链表头部和其他地方添加结点是不一样的。
在链表头部添加结点的关键代码为：
NodePointer ptr = new Node();
ptr->data = val;
ptr->next = head;
head = ptr;
在其他地方添加结点的关键代码为：
NodePointer ptr = new Node(), tmpPtr = head;
ptr->data = val;
while(...){...}
ptr->next = tmpPtr->next;
tmpPtr->next = ptr;
1.3 单链表删除节点
删除"节点30"
删除之前："节点20" 的后继节点为"节点30"，而"节点30" 的后继节点为"节点40"。
删除之后："节点20" 的后继节点为"节点40"。
需要注意的是在链表首部、尾部和其他地方删除结点是不一样的。
在链表首部删除结点的关键代码为：
NodePointer ptr = head, tmpPtr;
...if (pos == ) // 在链表第一个位置
{
head = ptr->next;
delete ptr;
}
在链表尾部删除结点的关键代码为：
NodePointer ptr = head, tmpPtr;
while (...){...}
tmpPtr = ptr->next;
ptr->next = NULL;
delete tmpPtr;
在其他地方删除结点的关键代码为：
NodePointer ptr = head, tmpPtr;
while(...){...}
tmpPtr = ptr->next;
ptr->next = tmpPtr->next;
delete tmpPtr;
2. 代码实现
对于单链表，我定义了一个这样的类LinkedList：
// linkedlist.h
#ifndef LINKEDLIST
#define LINKEDLIST #include <iostream>
#include <cassert> using namespace std; typedef int ElementType; class Node
{
public:
ElementType data;
Node * next;
};
typedef Node * NodePointer; class LinkedList
{
public:
LinkedList();
virtual ~LinkedList();
LinkedList(const LinkedList& origlist); // 拷贝构造函数
LinkedList& operator=(const LinkedList& origlist); // 赋值运算符重载
void initList(ElementType * arr, int len);
bool isEmpty();
bool addNode(const int pos, const ElementType val);
bool deleteNode(const int pos);
void displayNodes();
NodePointer getNode(const int pos);
int getLenOfList(); private:
NodePointer head; }; #endif // LINKEDLIST
实现代码如下：
// linkedlist.cpp
#include "linkedlist.h" LinkedList::LinkedList()
{
head = NULL;
} LinkedList::~LinkedList()
{
NodePointer ptr = head, tmpPtr;
while (ptr != NULL)
{
tmpPtr = ptr;
ptr = ptr->next;
delete tmpPtr;
}
} LinkedList::LinkedList(const LinkedList& origlist)
{
//head = origlist.head; // 很容易写成这样，这样会造成浅拷贝
NodePointer ptr = origlist.head;
int i = ;
while (ptr != NULL)
{
addNode(i, ptr->data);
ptr = ptr->next;
i++;
}
} LinkedList& LinkedList::operator=(const LinkedList& origlist)
{
//head = origlist.head; // 很容易写成这样，这样会造成浅拷贝
NodePointer ptr = origlist.head;
int i = ;
while (ptr != NULL)
{
addNode(i, ptr->data);
ptr = ptr->next;
i++;
}
return *this;
} void LinkedList::initList(ElementType * arr, int len)
{
for (int i = ; i < len; i++)
{
addNode(i, arr[i]);
}
} bool LinkedList::isEmpty()
{
return head == NULL;
} bool LinkedList::addNode(const int pos, const ElementType val)
{
bool success = true;
int len = getLenOfList();
// assert(0 <= pos <= len);
if (pos < || pos > len)
{
cerr << "The node at position " << pos << " you want to add is less than zero or larger than "
<< "the length of list ." << endl;
success = false;
throw out_of_range("out_of_range");
}
else
{
NodePointer ptr = new Node();
ptr->data = val;
if (pos == ) // 如果添加的元素在第1个
{
ptr->next = head;
head = ptr;
}
else // 其他
{
NodePointer tmpPtr = head;
int count = ;
while (tmpPtr != NULL && count < pos - )
{
tmpPtr = tmpPtr->next;
count++;
}
ptr->next = tmpPtr->next;
tmpPtr->next = ptr;
} } return success;
} bool LinkedList::deleteNode(const int pos)
{
bool success = true;
int len = getLenOfList();
if (len == )
{
cerr << "There is no element in the list." << endl;
success = false;
}
else
{
NodePointer ptr = head, tmpPtr;
int count = ;
// assert(0 <= pos <= len);
if (pos < || pos > len - )
{
cerr << "The node at position " << pos << " you want to delete is less than zero or larger than "
<< "the length of list ." << endl;
success = false;
throw out_of_range("out_of_range");
}
else if (pos == ) // 在链表第一个位置
{
head = ptr->next;
delete ptr;
}
else if (pos == len - ) // 在链表最后一个位置
{
while (ptr != NULL && count < pos - )
{
ptr = ptr->next;
count++;
}
tmpPtr = ptr->next;
ptr->next = NULL;
delete tmpPtr;
}
else // 其他
{
while (ptr != NULL && count < pos - )
{
ptr = ptr->next;
count++;
}
tmpPtr = ptr->next;
ptr->next = tmpPtr->next;
delete tmpPtr;
}
}
return success;
} void LinkedList::displayNodes()
{
int len = getLenOfList();
if (len == )
{
cerr << "There is no element in the list." << endl;
}
else
{
NodePointer ptr = head;
int sequence = ;
while (ptr != NULL)
{
cout << "Seq: " << sequence << "; Data: " << ptr->data << "."<< endl;;
ptr = ptr->next;
sequence++;
}
} } NodePointer LinkedList::getNode(const int pos)
{
int len = getLenOfList();
if (len == )
{
cerr << "There is no element in the list." << endl;
return NULL;
}
else
{
// assert(0 <= pos <= len);
if (pos < || pos > len - )
{
cerr << "The item at position " << pos << " you want to get is less than zero or "
<< "larger than the length of list." << endl;
throw out_of_range("out_of_range");
// return NULL;
}
else
{
NodePointer ptr = head;
int count = ;
while (ptr != NULL && count < pos)
{
ptr = ptr->next;
count++;
}
return ptr;
}
}
} int LinkedList::getLenOfList()
{
int len = ;
NodePointer ptr = head;
while (ptr != NULL)
{
len++;
ptr = ptr->next;
}
return len;
}
linkedlist.cpp
Boost单元测试代码如下：
// BoostUnitTest.cpp
#define BOOST_TEST_MODULE LinkedList_Test_Module #include "stdafx.h"
#include "D:\VSProject\Algorithm\List\LinkedList\SingleLinkedList_BasedOnPointer\SingleLinkedList\SingleLinkedList\linkedlist.h" struct LinkedList_Fixture
{
public:
LinkedList_Fixture()
{
testLinkedList = new LinkedList();
}
~LinkedList_Fixture()
{
delete testLinkedList;
} LinkedList * testLinkedList; }; BOOST_FIXTURE_TEST_SUITE(LinkedList_Test_Suite, LinkedList_Fixture) BOOST_AUTO_TEST_CASE( LinkedList_Normal_Test )
{
// isEmpty --------------------------------------------
BOOST_REQUIRE(testLinkedList->isEmpty() == true); // getLenOfList ---------------------------------------
BOOST_REQUIRE(testLinkedList->getLenOfList() == ); // addNode & getNode ---------------------------------
BOOST_REQUIRE(testLinkedList->addNode(, ) == true);
BOOST_REQUIRE((testLinkedList->getNode())->data == );
BOOST_REQUIRE((testLinkedList->getNode())->next == NULL);
BOOST_REQUIRE(testLinkedList->isEmpty() == false);
BOOST_REQUIRE(testLinkedList->getLenOfList() == ); BOOST_REQUIRE(testLinkedList->addNode(, ) == true);
BOOST_REQUIRE((testLinkedList->getNode())->data == );
BOOST_REQUIRE((testLinkedList->getNode())->next == NULL);
BOOST_REQUIRE(testLinkedList->isEmpty() == false);
BOOST_REQUIRE(testLinkedList->getLenOfList() == ); BOOST_REQUIRE(testLinkedList->addNode(, ) == true);
BOOST_REQUIRE((testLinkedList->getNode())->data == );
BOOST_REQUIRE((testLinkedList->getNode())->next != NULL);
BOOST_REQUIRE(testLinkedList->isEmpty() == false);
BOOST_REQUIRE(testLinkedList->getLenOfList() == ); // deleteNode -----------------------------------------
BOOST_REQUIRE(testLinkedList->deleteNode() == true);
BOOST_REQUIRE((testLinkedList->getNode())->data == );
BOOST_REQUIRE(testLinkedList->getLenOfList() == ); BOOST_REQUIRE(testLinkedList->deleteNode() == true);
BOOST_REQUIRE((testLinkedList->getNode())->data == );
BOOST_REQUIRE(testLinkedList->getLenOfList() == ); BOOST_REQUIRE(testLinkedList->deleteNode() == true);
BOOST_REQUIRE(testLinkedList->getLenOfList() == ); // initList -------------------------------------------
int arr[] = { , , };
int len = sizeof(arr) / sizeof(int);
testLinkedList->initList(arr, len);
BOOST_REQUIRE(testLinkedList->getLenOfList() == );
BOOST_REQUIRE((testLinkedList->getNode())->data == );
BOOST_REQUIRE((testLinkedList->getNode())->data == );
BOOST_REQUIRE((testLinkedList->getNode())->data == );
BOOST_REQUIRE((testLinkedList->getNode())->next == NULL); } BOOST_AUTO_TEST_CASE(LinkedList_Abnormal_Test)
{
int arr[] = { , , };
int len = sizeof(arr) / sizeof(int);
testLinkedList->initList(arr, len); // addNode -------------------------------------------
BOOST_REQUIRE_THROW(testLinkedList->addNode(-, ), out_of_range);
BOOST_REQUIRE_THROW(testLinkedList->addNode(, ), out_of_range); // deleteNode ----------------------------------------
BOOST_REQUIRE_THROW(testLinkedList->deleteNode(-), out_of_range);
BOOST_REQUIRE_THROW(testLinkedList->deleteNode(), out_of_range); // getNode --------------------------------------------
BOOST_REQUIRE_THROW(testLinkedList->getNode(-), out_of_range);
BOOST_REQUIRE_THROW(testLinkedList->getNode(), out_of_range); } BOOST_AUTO_TEST_CASE(LinkedList_CopyConstuctor_Test)
{
int arr[] = { , , };
int len = sizeof(arr) / sizeof(int);
testLinkedList->initList(arr, len); //LinkedList * testLinkedList2(testLinkedList); // 特别容易写成这样，这样导致的结果就是testLinkedList2和
// testLinkedList指向同一块内存这样的写法才是正确的
// 该句等同于
// LinkedList * testLinkedList2;
// testLinkedList2 = testLinkedList;
//LinkedList testLinkedList2(*testLinkedList); // 要不就这样子定义，只不过此时testLinkedList2不是一个指针
LinkedList * testLinkedList3 = new LinkedList(*testLinkedList);
BOOST_REQUIRE(testLinkedList3->getLenOfList() == );
BOOST_REQUIRE((testLinkedList3->getNode())->data == );
BOOST_REQUIRE((testLinkedList3->getNode())->data == );
BOOST_REQUIRE((testLinkedList3->getNode())->data == );
BOOST_REQUIRE((testLinkedList3->getNode())->next == NULL);
} BOOST_AUTO_TEST_CASE(LinkedList_EqualOperator_Test)
{
int arr[] = { , , };
int len = sizeof(arr) / sizeof(int);
testLinkedList->initList(arr, len); // LinkedList * testLinkedList2 = testLinkedList; // 错误的写法
LinkedList * testLinkedList2 = new LinkedList();
*testLinkedList2 = *testLinkedList; BOOST_REQUIRE(testLinkedList2->getLenOfList() == );
BOOST_REQUIRE((testLinkedList2->getNode())->data == );
BOOST_REQUIRE((testLinkedList2->getNode())->data == );
BOOST_REQUIRE((testLinkedList2->getNode())->data == );
BOOST_REQUIRE((testLinkedList2->getNode())->next == NULL);
} BOOST_AUTO_TEST_SUITE_END()
BoostUnitTest.cpp
本篇博文的代码均托管到Taocode : http://code.taobao.org/p/datastructureandalgorithm/src/.