如何在矢量图中进行线性搜索？

Question

我正在写一个电影程序。 findFilmsByRating需要返回具有指定等级或更低等级的电影集。例如，调用具有FILM_RATING_PG_13参数的findFilmsByRating应该返回具有等级PG 13，PG和G的所有电影。任何帮助将被感激。

#include <iostream> 
#include <vector> 
#include <string> 

using namespace std; 

struct Film { 
int id;    // the unique id of the film 
string name;   // the film's name 
string description; // the film's description 
int runningTime;  // the film's running time in minutes <= 180 
int rating;   // the film's rating, from the const decls 
Film& operator =(const Film& bok); 
bool operator ==(const Film& bok); 

}; 
const int FILM_RATING_G = 0; 
const int FILM_RATING_PG = 1; 
const int FILM_RATING_PG_13 = 2; 
const int FILM_RATING_R = 3; 
const int FILM_RATING_NC_17 = 4; 
const int FILM_RATING_UNRATED = 5; 

bool Film::operator ==(const Film& bok) 
{ 
    return (runningTime == bok.runningTime&&rating == bok.rating&&name == 
    bok.name&&description == bok.description); 
    } 

Film& Film::operator=(const Film& bok) 
    { 
     if (*this == bok) 
     return *this; 
    else 
    { 
    runningTime = bok.runningTime; 
    description = bok.description; 
    name = bok.name; 
    rating = bok.rating; 
    } 
    return *this; 
} 

//function Def 
    void print(const vector<Film> &films); 
    vector <Film> selectionSort(vector <Film> films); 
    int find_smallest(const vector<Film>& vec, int index); 
    void my_swap(Film& obj_one, Film& obj_two); 
    vector <Film> findFilmsByRating(int rating, vector <Film> films); 
string filmRatingToString(int rating); 
vector <Film> findFilmsByRatingAndRunningTime(int rating, int runningTimes 
    vector <Film> films); 

int main() 
{ 
vector<Film> films; 
films.push_back(Film()); 
films[0].id = 0; 
films[0].name = "Three Kings"; 
films[0].description = "Army soldiers steal lots of gold"; 
films[0].runningTime = 114; 
films[0].rating = FILM_RATING_R; 

films.push_back(Film()); 

films[1].id = 1; 
films[1].name = "Eagle Eye"; 
films[1].description = "Threatening their lives and family, the unseen caller uses everyday technology to control their actions and push them into increasing danger. "; 
films[1].runningTime = 118; 
films[1].rating = FILM_RATING_PG_13; 

films.push_back(Film()); 

films[2].id = 2; 
films[2].name = "Blade Runner"; 
films[2].description = "A Blade Runner must pursue and try to terminate four replicants"; 
films[2].runningTime = 117; 
films[2].rating = FILM_RATING_R; 

films.push_back(Film()); 

films[3].id = 3; 
films[3].name = "Limitless"; 
films[3].description = "A mysterious pill helps a man use 100% of his brain"; 
films[3].runningTime = 105; 
films[3].rating = FILM_RATING_PG_13; 


films.push_back(Film()); 
films[4].id = 4; 
films[4].name = "Inception"; 
films[4].description = "Invading dream and changeing thoughts"; 
films[4].runningTime = 105; 
films[4].rating = FILM_RATING_PG_13; 

films.push_back(Film()); 
films[5].id = 5; 
films[5].name = "Twilight"; 
films[5].description = "Sparkly vampires"; 
films[5].runningTime = 122; 
films[5].rating = FILM_RATING_PG_13; 

films.push_back(Film()); 
films[6].id = 6; 
films[6].name = "Twilight New Moon"; 
films[6].description = "Sparkly vampires, and now a hot warewolf."; 
films[6].runningTime = 130; 
films[6].rating = FILM_RATING_PG_13; 

films.push_back(Film()); 
films[7].id = 7; 
films[7].name = "The lovely bones"; 
films[7].description = "Murder victim helps find killer from otherside."; 
films[7].runningTime = 122; 
films[7].rating = FILM_RATING_PG_13; 

films.push_back(Film()); 
films[8].id = 8; 
films[8].name = "Promethis"; 
films[8].description = "Pre-aleins"; 
films[8].runningTime = 124; 
films[8].rating = FILM_RATING_R; 

films.push_back(Film()); 
films[9].id = 9; 
films[9].name = "The Hunger Games"; 
films[9].description = "Girl gets taken from home to fight to the death for rich people."; 
films[9].runningTime = 142; 
films[9].rating = FILM_RATING_PG_13; 

films.push_back(Film()); 
films[10].id = 10; 
films[10].name = "Baby Driver"; 
films[10].description = "Kid with headphone drives the get away car."; 
films[10].runningTime = 113; 
films[10].rating = FILM_RATING_R; 

print(films); 
films = selectionSort(films); 

int rating = 0; 

films = findFilmsByRating (rating,films); 
cout << "****List of Movies by rating******" << endl; 
for (int i = 0; i < films.size(); ++i) 
{ 
    cout << endl; 
    cout << "Film title:  " << films[i].name << endl; 
    cout << "Film description: " << films[i].description << endl; 
    cout << "Film runtime:  " << films[i].runningTime << endl; 
    cout << "Film rating:  " << films[i].rating << endl; 
} 

    system("PAUSE"); 
} 
void print(const vector<Film> &films) 
{ 


cout << "****List of Movies******" << endl; 
for (int i = 0; i < films.size(); ++i) 
{ 
    cout << endl; 
    cout <<"Film title:  "<< films[i].name << endl; 
    cout <<"Film description: "<< films[i].description << endl; 
    cout <<"Film runtime:  "<<films[i].runningTime << endl; 
    cout <<"Film rating:  "<< films[i].rating << endl; 
    } 
} 


vector<Film> selectionSort(vector<Film> films) 
{ 
    for (unsigned int count = 0; count <films.size(); count++) 
{ 
    int ind_to_swap = find_smallest(films, count); 
    my_swap(films[count], films[ind_to_swap]); 
} 
    cout << "******** List by Run time *********" << endl; 
     for (int i = 0; i < films.size(); ++i) 
{ 
    cout << endl; 
    cout << "Film title:  " << films[i].name << endl; 
    cout << "Film description: " << films[i].description << endl; 
    cout << "Film runtime:  " << films[i].runningTime << endl; 
    cout << "Film rating:  " << films[i].rating << endl; 
    } 

    return vector<Film>(); 
    } 

    int find_smallest(const vector<Film>& vec, int index) 
    { 
     int smallest_index = index; 
     Film temp = vec[index]; 

for (unsigned int i = index; i <vec.size(); i++) 
{ 
    if (vec[i].runningTime <temp.runningTime) 
    { 
     smallest_index = i; 
     temp = vec[i]; 
    } 
    } 

    return smallest_index; 
    } 

    void my_swap(Film & obj_one, Film & obj_two) 
{ 
    Film temp = obj_one; 
    obj_one = obj_two; 
    obj_two = temp; 
    } 

vector<Film> findFilmsByRating(int rating, vector<Film> films) 
    { 
    int nIndex; 

    for (nIndex = 0; nIndex < films.size(); nIndex++) 
{ 
    if (rating == films[nIndex].rating) 
    { 
     return vector<Film>(rating); 
    } 
} 
return vector<Film>(); 
} 

Answer 1

创建一个新的vector存储匹配要求的评价

vector<Film> findFilmsByRating(int rating, vector<Film> films) 
{ 
    int nIndex; 
    vector<Film> results; 

    for (nIndex = 0; nIndex < films.size(); nIndex++) 
    { 
     if (rating == films[nIndex].rating) 
     { 
      results.push_back(films[nIndex]); 
     } 
    } 
    return results; 
} 

有也极有可能是一个function in the algorithms library你可以用做部分或全部工作，为您的电影。如果可能的话，站在巨人的肩膀上。