QUESTION $3$

Graph Data Structure

cpp

#include

#include

#include

#include

#include

#include

class ClubHub $\{$

private:

std::unordered$\_$map$>$ studentClubs;

std::unordered$\_$map$>$ clubMembers;

public:

void addStudent$($const std::string& studentID$)\{$

studentClubs$[$studentID$]=$ std::unordered$\_$set$()$;

$\}$

void createClub$($const std::string& clubName$)\{$

clubMembers$[$clubName$]=$ std::unordered$\_$set$()$;

$\}$

void addStudentToClub$($const std::string& studentID, const std::string& clubName$)\{$

studentClubs$[$studentID$].$insert$($clubName$)$;

clubMembers$[$clubName$].$insert$($studentID$)$;

$\}$

void removeStudentFromClub$($const std::string& studentID, const std::string& clubName$)\{$

studentClubs$[$studentID$].$erase$($clubName$)$;

clubMembers$[$clubName$].$erase$($studentID$)$;

$\}$

std::vector findClubsByStudent$($const std::string& studentID$)$ const $\{$

std::vector clubs$($studentClubs$.$at$($studentID$).$begin$(),$ studentClubs.at$($studentID$).$end$())$;

return clubs;

$\}$

std::vector findStudentsByClub$($const std::string& clubName$)$ const $\{$

std::vector students$($clubMembers$.$at$($clubName$).$begin$(),$ clubMembers.at$($clubName$).$end$())$;

return students;

$\}$

std::vector sortStudentsAlphabetically$()$ const $\{$

std::vector students;

for $($const auto& pair : studentClubs$)\{$

students.push$\_$back$($pair$.$first$)$;

$\}$

std::sort$($students$.$begin$(),$ students.end$())$;

return students;

$\}$

void saveToFile$($const std::string& filename$)$ const $\{$

std::ofstream file$($filename$)$;

for $($const auto& pair : studentClubs$)\{$

file $<<$ pair.first $<<"$:$"$;

for $($const auto& club : pair.second$)\{$

file $<<$ club $<<","$;

$\}$

file $<<"$

$"$;

$\}$

file.close$()$;

$\}$

void loadFromFile$($const std::string& filename$)\{$

std::ifstream file$($filename$)$;

std::string line;

while $($std::getline$($file$,$ line$))\{$

size$\_$t pos $=$ line.find$("$:$")$;

std::string studentID $=$ line.substr$(0,$ pos$)$;

std::string clubs $=$ line.substr$($pos $+1)$;

std::vector clubList;

size$\_$t start $=0,$ end;

while $(($end $=$ clubs.find$(",",$ start$))!=$ std::string::npos$)\{$

clubList.push$\_$back$($clubs$.$substr$($start$,$ end $-$ start$))$;

start $=$ end $+1$;

$\}$

studentClubs$[$studentID$]=$ std::unordered$\_$set$($clubList$.$begin$(),$ clubList.end$())$;

for $($const auto& club : clubList$)\{$

clubMembers$[$club$].$insert$($studentID$)$;

$\}$

$\}$

file.close$()$;

$\}$

$\}$;