Решение всех задач из учебника Стивена Праты

// queue.h -- interface for a queue
#ifndef QUEUE_H_
#define QUEUE_H_
// This queue will contain Customer items
class Customer
{
private:
    long arrive;        // arrival time for customer
    int processtime;    // processing time for customer
public:
    Customer() : arrive(0), processtime (0){}
    void set(long when);
    long when() const { return arrive; }
    int ptime() const { return processtime; }
};
 
typedef Customer Item;
 
class Queue
{
private:
// class scope definitions
    // Node is a nested structure definition local to this class
    struct Node { Item item; struct Node * next;};
    enum {Q_SIZE = 10};
// private class members
    Node * front;       // pointer to front of Queue
    Node * rear;        // pointer to rear of Queue
    int items;          // current number of items in Queue
    const int qsize;    // maximum number of items in Queue
    // preemptive definitions to prevent public copying
    Queue(const Queue & q) : qsize(0) { }
    Queue & operator=(const Queue & q) { return *this;}
public:
    Queue(int qs = Q_SIZE); // create queue with a qs limit
    ~Queue();
    bool isempty() const;
    bool isfull() const;
    int queuecount() const;
    bool enqueue(const Item &item); // add item to end
    bool dequeue(Item &item);       // remove item from front
};
#endif

// queue.cpp -- Queue and Customer methods
#include "queue.h"
#include <cstdlib>         // (or stdlib.h) for rand()
 
// Queue methods
Queue::Queue(int qs) : qsize(qs)
{
    front = rear = NULL;    // or nullptr
    items = 0;
}
 
Queue::~Queue()
{
    Node * temp;
    while (front != NULL)   // while queue is not yet empty
    {
        temp = front;       // save address of front item
        front = front->next;// reset pointer to next item
        delete temp;        // delete former front
    }
}
 
bool Queue::isempty() const
{
    return items == 0;
}
 
bool Queue::isfull() const
{
    return items == qsize;
}
 
int Queue::queuecount() const
{
    return items;
}
 
// Add item to queue
bool Queue::enqueue(const Item & item)
{
    if (isfull())
        return false;
    Node * add = new Node;  // create node
// on failure, new throws std::bad_alloc exception
    add->item = item;       // set node pointers
    add->next = NULL;       // or nullptr;
    items++;
    if (front == NULL)      // if queue is empty,
        front = add;        // place item at front
    else
        rear->next = add;   // else place at rear
    rear = add;             // have rear point to new node
    return true;
}
 
// Place front item into item variable and remove from queue
bool Queue::dequeue(Item & item)
{
    if (front == NULL)
        return false;
    item = front->item;     // set item to first item in queue
    items--;
    Node * temp = front;    // save location of first item
    front = front->next;    // reset front to next item
    delete temp;            // delete former first item
    if (items == 0)
        rear = NULL;
    return true;
}
 
// customer method
 
// when is the time at which the customer arrives
// the arrival time is set to when and the processing
// time set to a random value in the range 1 - 3
void Customer::set(long when)
{
    processtime = std::rand() % 3 + 1;
    arrive = when; 
}

// bank.cpp -- using the Queue interface
// compile with queue.cpp
#include <iostream>
#include <cstdlib> // for rand() and srand()
#include <ctime>   // for time()
#include "queue.h"
const int MIN_PER_HR = 60;
 
bool newcustomer(double x); // is there a new customer?
 
int main()
{
    using std::cin;
    using std::cout;
    using std::endl;
    using std::ios_base;
// setting things up
    std::srand(std::time(0));    //  random initializing of rand()
 
    cout << "Case Study: Bank of Heather Automatic Teller\n";
    cout << "Enter maximum size of queue: ";
    int qs;
    cin >> qs;
    Queue line(qs);         // line queue holds up to qs people
 
    cout << "Enter the number of simulation hours: ";
    int hours;              //  hours of simulation
    cin >> hours;
    // simulation will run 1 cycle per minute
    long cyclelimit = MIN_PER_HR * hours; // # of cycles
 
    cout << "Enter the average number of customers per hour: ";
    double perhour;         //  average # of arrival per hour
    cin >> perhour;
    double min_per_cust;    //  average time between arrivals
    min_per_cust = MIN_PER_HR / perhour;
 
    Item temp;              //  new customer data
    long turnaways = 0;     //  turned away by full queue
    long customers = 0;     //  joined the queue
    long served = 0;        //  served during the simulation
    long sum_line = 0;      //  cumulative line length
    int wait_time = 0;      //  time until autoteller is free
    long line_wait = 0;     //  cumulative time in line
 
 
// running the simulation
    for (int cycle = 0; cycle < cyclelimit; cycle++)
    {
        if (newcustomer(min_per_cust))  // have newcomer
        {
            if (line.isfull())
                turnaways++;
            else
            {
                customers++;
                temp.set(cycle);    // cycle = time of arrival
                line.enqueue(temp); // add newcomer to line
            }
        }
        if (wait_time <= 0 && !line.isempty())
        {
            line.dequeue (temp);      // attend next customer
            wait_time = temp.ptime(); // for wait_time minutes
            line_wait += cycle - temp.when();
            served++;
        }
        if (wait_time > 0)
            wait_time--;
        sum_line += line.queuecount();
    }
 
// reporting results
    if (customers > 0)
    {
        cout << "customers accepted: " << customers << endl;
        cout << "  customers served: " << served << endl;
        cout << "         turnaways: " << turnaways << endl;
        cout << "average queue size: ";
        cout.precision(2);
        cout.setf(ios_base::fixed, ios_base::floatfield);
        cout << (double) sum_line / cyclelimit << endl;
        cout << " average wait time: "
             << (double) line_wait / served << " minutes\n";
    }
    else
        cout << "No customers!\n";
    cout << "Done!\n";
    // cin.get();
    // cin.get();
    return 0;
}
 
//  x = average time, in minutes, between customers
//  return value is true if customer shows up this minute
bool newcustomer(double x)
{
    return (std::rand() * x / RAND_MAX < 1); 
}

// string1.h -- fixed and augmented string class definition
 
#ifndef STRING1_H_
#define STRING1_H_
#include <iostream>
using std::ostream;
using std::istream;
 
class String
{
private:
    char * str;             // pointer to string
    int len;                // length of string
    static int num_strings; // number of objects
    static const int CINLIM = 80;  // cin input limit
public:
// constructors and other methods
    String(const char * s); // constructor
    String();               // default constructor
    String(const String &); // copy constructor
    ~String();              // destructor
    int length () const { return len; }
// overloaded operator methods    
    String & operator=(const String &);
    String & operator=(const char *);
    char & operator[](int i);
    const char & operator[](int i) const;
    String operator+(const String& rb) const;
    void stringlow();
    void stringup();
    int has(char ch) const;
// overloaded operator friends
    friend bool operator<(const String &st, const String &st2);
    friend bool operator>(const String &st1, const String &st2);
    friend bool operator==(const String &st, const String &st2);
    friend ostream & operator<<(ostream & os, const String & st);
    friend istream & operator>>(istream & is, String & st);
    friend String operator+(const char* ch, const String& rb);
// static function
    static int HowMany();
};
#endif

// string1.cpp -- String class methods
//#include <cstring>                 // string.h for some
#include "string1.h"               // includes <iostream>
#include <cctype>
using std::cin;
using std::cout;
 
// initializing static class member
 
int String::num_strings = 0;
 
// static method
int String::HowMany()
{
    return num_strings;
}
 
// class methods
String::String(const char * s)     // construct String from C string
{
    len = std::strlen(s);          // set size
    str = new char[len + 1];       // allot storage
    strcpy_s(str, len + 1, s);           // initialize pointer
    num_strings++;                 // set object count
}
 
String::String()                   // default constructor
{
    len = 4;
    str = new char[1];
    str[0] = '\0';                 // default string
    num_strings++;
}
 
String::String(const String & st)
{
    num_strings++;             // handle static member update
    len = st.len;              // same length
    str = new char [len + 1];  // allot space
    strcpy_s(str, len + 1, st.str);  // copy string to new location
}
 
String::~String()                     // necessary destructor
{
    --num_strings;                    // required
    delete [] str;                    // required
}
 
// overloaded operator methods    
 
    // assign a String to a String
int String::has(char ch) const
{
    int ac = 0;
    for (int i = 0; *(str + i) != '\0'; i++)
    {
        if (*(str + i) == ch)
            ++ac;
    }
    return ac;
}
 
void String::stringup()
{
    for (int i = 0; *(str + i) != '\0'; i++)
    {
        *(str + i) = toupper(*(str + i));
    }
}
 
void String::stringlow()
{
    for (int i = 0; *(str + i) != '\0'; i++)
    {
        *(str + i) = tolower(*(str + i));
    }
}
 
String operator+(const char* ch, const String& rb)
{
    int cch = strlen(ch);
    char* buff = new char[cch + rb.len + 1];
    for (int i = 0; i < cch; i++)
    {
        *(buff + i) = *(ch + i);
    }
    for (int i = 0; i < rb.len; i++)
    {
        *(buff + cch + i) = *(rb.str + i);
    }
    *(buff + cch + rb.len) = '\0';
 
    String temp(buff);
    delete[] buff;
    return temp;
}
 
String String::operator+(const String& rb) const
{
    char* buff = new char[this->len + rb.len + 1];
    for (int i = 0; i < this->len; i++)
    {
        *(buff + i) = *(this->str + i);
    }
    for (int i = 0; i < rb.len; i++)
    {
        *(buff + this->len + i) = *(rb.str + i);
    }
    *(buff + this->len + rb.len) = '\0';
 
    String temp(buff);
    delete[] buff;
    return temp;
}
 
String & String::operator=(const String & st)
{
    if (this == &st)
        return *this;
    delete [] str;
    len = st.len;
    str = new char[len + 1];
    strcpy_s(str, len + 1, st.str);
    return *this;
}
 
    // assign a C string to a String
String & String::operator=(const char * s)
{
    delete [] str;
    len = std::strlen(s);
    str = new char[len + 1];
    strcpy_s(str, len + 1, s);
    return *this;
}
 
    // read-write char access for non-const String
char & String::operator[](int i)
{
    return str[i];
}
 
    // read-only char access for const String
const char & String::operator[](int i) const
{
    return str[i];
}
 
// overloaded operator friends
 
bool operator<(const String &st1, const String &st2)
{
    return (std::strcmp(st1.str, st2.str) < 0);
}
 
bool operator>(const String &st1, const String &st2)
{
    return st2 < st1;
}
 
bool operator==(const String &st1, const String &st2)
{
    return (std::strcmp(st1.str, st2.str) == 0);
}
 
    // simple String output
ostream & operator<<(ostream & os, const String & st)
{
    os << st.str;
    return os; 
}
 
    // quick and dirty String input
istream & operator>>(istream & is, String & st)
{
    char temp[String::CINLIM];
    is.get(temp, String::CINLIM);
    if (is)
        st = temp;
    while (is && is.get() != '\n')
        continue;
    return is; 
}

#include <iostream>
#include <string>
#include "string1.h"
 
using namespace std;
 
int main()
{
    String s1(" and I am a C++ student.");
    String s2 = "Pleace enter your name: ";
    String s3;
    cout << s2;
    cin >> s3;
    s2 = "My name is " + s3;
    cout << s2 << ".\n";
    s2 = s2 + s1;
    s2.stringup();
    cout << "The string\n" << s2 << "\ncontains " << s2.has('A')
        << " 'A' characters in it.\n";
    s1 = "red";
 
    String rgb[3] = { String(s1), String("green"), String("blue") };
    cout << "Enter the name of a primary color for mixing light: ";
    String ans;
    bool success = false;
    while (cin >> ans)
    {
        ans.stringlow();
        for (int i = 0; i < 3; i++)
        {
            if (ans == rgb[i])
            {
                cout << "That's right!\n";
                success = true;
                break;
            }
        }
        if (success)
            break;
        else
            cout << "Tru again!\n";
    }
    cout << "Bye\n";
    
 
    cin.get();
    cin.get();
    return 0;
}