使用指针计算堆栈问题的大 O 表示法

嗨，谁能帮我使用 Big O 表示法计算此代码的算法复杂性？我对使用 Big O 不太了解，因为此代码中有很多指针。我只知道一些代码。像cout是O(1(。其余的我不明白。我只是编程的初学者。请帮我数一数大o符号。谢谢。

#include <iostream>
#include <string>
#include <stdlib.h>
using namespace std;
class Book {
int year, page;
unsigned long long int code;
string language, name, title;
Book *head, *next, *prev, *link;
public:
Book (string & name, string & title, unsigned long long int code, string & language, int year, int page) {
head = NULL;
this->name = name;
this->title = title;
this->language = language;
this->code = code;
this->year = year;
this->page = page;
}
~Book (void) {
delete head;
}
void display (void);
void add (void);
void dellete (void);
};
void Book::add(void) {
string name, title, language;
int year, page;
unsigned long long int code;
cout << "Add a book...";
cout << endl << "Authortt:", cin >> name;
cout << "Titlett:", cin >> title;
cout << "ISBN(13 digits)t:", cin >> code;
cout << "Languaget:", cin >> language;
cout << "Yeartt:", cin >> year;
cout << "Pagestt:", cin >> page;
Book* p = new Book(name, title, code, language, year, page);
p->next = head;
head = p;
}
void Book::dellete(void) {
string name, title, language;
int year, page;
unsigned long long int code;
Book* p, *prev, *next;
if(head==NULL) {
cout << "There is no book in the stackn";
} else if(head->next==NULL) {
p = head;
head = NULL;
free(p);
cout << "All book has been taken. Now the stack is emptyn";
} else{
p = head;
head = p->next;
free(p);
cout << "A book has been takenn";
}
}
void Book::display(void) {
Book* p = head;
cout << "Displaying book(s)...n";
while (p) {
cout << "----------------------------- n";
cout << "Authortt:" << p->name << endl;
cout << "Titlett:" << p->title << endl;
cout << "ISBNtt:" << p->code << endl;
cout << "Languaget:" << p->language << endl;
cout << "Yeartt:" << p->year << endl;
cout << "Pagestt:" << p->page << endl;
cout << endl;
p = p->next;
}
}
int main (int argc, char const** argv) {
string blank = "";
Book* B = new Book(blank, blank, 0, blank, 0, 0);
int opt;
for (;;) {
cout << "----------------------------- n";
cout << "1) Add a book.n";
cout << "2) Show all books.n";
cout << "3) Take a bookn";
cout << "4) Exit. n";
cout << "Don't use space but use underscore...nn";
cout << "Options:", cin >> opt;
switch (opt) {
case 1:
B->add();
break;
case 2:
B->display();
break;
case 3:
B->dellete();
break;
case 4:
exit(0);
default:
continue;
}
}
return 0;
}