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第七课  堆栈与队列

一、数据结构的基本概念

1.逻辑结构

1)集合结构(集)：结构中的元素除了同属一个集之外，没有任何联系。

2)线性结构(表)：结构中的元素具有一对一的前后关系。

3)树型结构(树)：结构中的元素具有一对多的父子关系。

4)网状结构(图)：结构中的元素具有多对多的交叉映射关系。

2.物理结构

1)顺序结构(数组)：结构中的元素存放在一段连续的地址空间中。随机访问方便，空间利用率低，插入删除不便。

2)链式结构(链式)：结构中的元素存放在彼此独立的地址空间中，每个独立的地址空间被称为节点，节点除了保存数据以外，还保存另外一个或几个相关节点的地址。空间利用率高，插入删除方便，随机访问不便。

3.逻辑结构和物理结构的关系

表    树  图

顺序 数组 顺序树 复  

链式 链表 链式树 合

二、数据结构的基本运算

1.创建与销毁

2.插入与删除

3.获取与修改

4.排序与查找

三、堆栈

1.基本特征：后进先出

2.基本操作：压入(push)，弹出(pop)

3.实现要点：初始化空间，栈顶指针，判空判满。

1234

1*9^3+2*9^2+3*9^1+4*9^0 -> 4

123 -> 3

12 -> 2

1 -> 1

#include <iostream>
#include <fstream>
using namespace std;
int main (void) {ofstream ofs ("format.txt");if (! ofs) {perror ("打开文件失败");return -1;}ofs << 1234 << ' ' << 56.78 << ' ' << "tarena"<< '\n';ofs.close ();ofs.open ("format.txt", ios::app);if (! ofs) {perror ("打开文件失败");return -1;}ofs << "append_a_line\n";ofs.close ();ifstream ifs ("format.txt");if (! ifs) {perror ("打开文件失败");return -1;}int i;double d;string s1, s2;ifs >> i >> d >> s1 >> s2;cout << i << ' ' << d << ' ' << s1 << ' '<< s2 << endl;ifs.close ();return 0;
}

#include <iostream>
using namespace std;
// 基于链式表的堆栈
class Stack {
public:// 构造过程中初始化为空堆栈Stack (void) : m_top (NULL) {}// 析构过程中销毁剩余的节点~Stack (void) {for (Node* next; m_top; m_top = next) {next = m_top->m_next;delete m_top;}}// 压入void push (int data) {/*Node* node = new Node;node->m_data = data;node->m_next = m_top;m_top = node;*/m_top = new Node (data, m_top);}// 弹出int pop (void) {if (empty ())throw UnderFlow ();int data = m_top->m_data;Node* next = m_top->m_next;delete m_top;m_top = next;return data;}// 判空bool empty (void) const {return ! m_top;}
private:// 下溢异常class UnderFlow : public exception {const char* what (void) const throw () {return "堆栈下溢！";}};// 节点class Node {public:Node (int data = 0, Node* next = NULL) :m_data (data), m_next (next) {}int m_data; // 数据Node* m_next; // 后指针
    };Node* m_top; // 栈顶
};
int main (void) {try {Stack stack;for (int i = 0; i < 10; ++i)stack.push (i);while (! stack.empty ())cout << stack.pop () << endl;
//        stack.pop ();
    }catch (exception& ex) {cout << ex.what () << endl;return -1;}return 0;
}

#include <iostream>
#include <fstream>
using namespace std;
int main (void) {ofstream ofs ("putget.txt");if (! ofs) {perror ("打开文件失败");return -1;}for (char c = ' '; c <= '~'; ++c)if (! ofs.put (c)) {perror ("写入文件失败");return -1;}ofs.close ();ifstream ifs ("putget.txt");if (! ifs) {perror ("打开文件失败");return -1;}char c;while ((c = ifs.get ()) != EOF)cout << c;cout << endl;if (! ifs.eof ()) {perror ("读取文件失败");return -1;}ifs.close ();return 0;
}

#include <iostream>
#include <fstream>
using namespace std;
int main (void) {fstream fs ("seek.txt", ios::in | ios::out);if (! fs) {perror ("打开文件失败");return -1;}fs << "0123456789";cout << fs.tellp () << endl;cout << fs.tellg () << endl;fs.seekp (-3, ios::cur);fs << "XYZ";fs.seekg (4, ios::beg);int i;fs >> i;cout << i << endl;cout << fs.tellg () << endl;cout << fs.tellp () << endl;fs.seekg (-6, ios::end);fs << "ABC";fs.close ();return 0;
}

#include <iostream>
using namespace std;
// 基于顺序表的堆栈
class Stack {
public:// 构造过程中分配内存Stack (size_t size = 10) :m_array (new int[size]), m_size (size),m_top (0) {}// 析构过程中释放内存~Stack (void) {if (m_array) {delete[] m_array;m_array = 0;}}// 压入void push (int data) {if (full ())throw OverFlow ();m_array[m_top++] = data;}// 弹出int pop (void) {if (empty ())throw UnderFlow ();return m_array[--m_top];}// 判满bool full (void) const {return m_top >= m_size;}// 判空bool empty (void) const {return ! m_top;}
private:// 上溢异常class OverFlow : public exception {const char* what (void) const throw () {return "堆栈上溢！";}};// 下溢异常class UnderFlow : public exception {const char* what (void) const throw () {return "堆栈下溢！";}};int* m_array; // 数组size_t m_size; // 容量size_t m_top; // 栈顶
};
void printb (unsigned int numb, int base) {Stack stack (256);do {stack.push (numb % base);}    while (numb /= base);while (! stack.empty ()) {int digit = stack.pop ();if (digit < 10)cout << digit;elsecout << char (digit - 10 + 'A');}cout << endl;
}
int main (void) {try {Stack stack;for (int i = 0; ! stack.full (); ++i)stack.push (i);
//        stack.push (0);while (! stack.empty ())cout << stack.pop () << endl;
//        stack.pop ();
    }catch (exception& ex) {cout << ex.what () << endl;return -1;}cout << "输入一个整数：" << flush;int numb;cin >> numb;cout << "您想看几进制：" << flush;int base;cin >> base;cout << "结果：";printb (numb, base);return 0;
}

#include <iostream>
#include <iomanip>
#include <cmath>
#include <fstream>
#include <sstream>
using namespace std;
int main (void) {cout << sqrt (2) << endl;cout.precision (10); // 10位有效数字cout << sqrt (2) << endl;cout << sqrt (2) * 100 << endl;cout << setprecision (5) << sqrt (2) << endl<< sqrt (2) * 100 << endl;cout << "当前精度：" << cout.precision ()<< endl;cout << setprecision (2) << 1.24 << ' ' << 1.25<< ' ' << 1.26 << endl;cout << showbase << hex << 127 << endl;cout << oct << 127 << endl;cout << dec << 127 << endl;cout << noshowbase << hex << 127 << dec << endl;cout << setw (12) << 127 << 721 << endl;cout << setfill ('$') << left << setw (12)<< 127 << endl;cout.precision (10);cout.setf (ios::scientific);cout << sqrt (2) << endl;cout.setf (ios::fixed);cout << sqrt (2) << endl;cout << 12.00 << endl;cout << showpoint << 12.00 << endl;cout << noshowpoint << 12.00 << endl;ifstream ifs ("stream.txt");ifs.unsetf (ios::skipws);char c;while (ifs >> c)cout << c;ifs.setf (ios::skipws);ifs.clear (); // 复位
    ifs.seekg (ios::beg);while (ifs >> c)cout << c;ifs.close ();cout << endl;int i = 1234;double d = 56.78;string s = "tarena";ostringstream oss;oss << i << ' ' << d << ' ' << s;string str = oss.str ();cout << str << endl;str = "hello 3.14 pai";istringstream iss;iss.str (str);iss >> s >> d >> str;cout << s << ' ' << d << ' ' << str << endl;return 0;
}

#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;
class Dog {
public:Dog (const string& name = "", int age = 0) :m_age (age) {strcpy (m_name, name.c_str ());}void print (void) const {cout << m_name << "，" << m_age << endl;}
private:char m_name[128];int m_age;
};
int main (void) {ofstream ofs ("dog.dat");Dog dog ("小白", 25);ofs.write ((char*)&dog, sizeof (dog));ofs.close ();ifstream ifs ("dog.dat");Dog dog2;ifs.read ((char*)&dog2, sizeof (dog2));dog2.print ();ifs.close ();return 0;
}

#include <iostream>
#include <fstream>
#include <stdexcept>
#include <cstdlib>
using namespace std;
#define BUFSIZE (1024*10)
int _xor (const char* src, const char* dst,unsigned char key) {ifstream ifs (src, ios::binary);if (! ifs) {perror ("打开源文件失败");return -1;}ofstream ofs (dst, ios::binary);if (! ofs) {perror ("打开目标文件失败");return -1;}char* buf = NULL;try {buf = new char[BUFSIZE];}catch (bad_alloc& ex) {cout << ex.what () << endl;return -1;}while (ifs.read (buf, BUFSIZE)) {for (size_t i = 0; i < BUFSIZE; ++i)buf[i] ^= key;if (! ofs.write (buf, BUFSIZE)) {perror ("写入文件失败");return -1;}}if (! ifs.eof ()) {perror ("读取文件失败");return -1;}for (size_t i = 0; i < ifs.gcount (); ++i)buf[i] ^= key;if (! ofs.write (buf, ifs.gcount ())) {perror ("写入文件失败");return -1;}delete[] buf;ofs.close ();ifs.close ();return 0;
}
int enc (const char* plain, const char* cipher) {srand (time (NULL));unsigned char key = rand () % 256;if (_xor (plain, cipher, key) == -1)return -1;cout << "密钥：" << (unsigned int)key << endl;return 0;
}
int dec (const char* cipher, const char* plain,unsigned char key) {return _xor (cipher, plain, key);
}
int main (int argc, char* argv[]) {if (argc < 3) {cerr << "用法：" << argv[0]<< " <明文文件> <密文文件>" << endl;cerr << "用法：" << argv[0]<< " <密文文件> <明文文件> <密钥>"<< endl;return -1;}if (argc < 4)return enc (argv[1], argv[2]);elsereturn dec (argv[1], argv[2],atoi (argv[3]));return 0;
}