MeisamMulla · May 18, 2020 08:07
diff --git a/runoff.c b/runoff.c
 #include <cs50.h>
 #include <stdio.h>
 #include <string.h>

 // Max voters and candidates
 #define MAX_VOTERS 100
 #define MAX_CANDIDATES 9

 // preferences[i][j] is jth preference for voter i
 int preferences[MAX_VOTERS][MAX_CANDIDATES];

 // Candidates have name, vote count, eliminated status
 typedef struct
 {
    string name;
    int votes;
    bool eliminated;
 }
 candidate;

 // Array of candidates
 candidate candidates[MAX_CANDIDATES];

 // Numbers of voters and candidates
 int voter_count;
 int candidate_count;

 // Function prototypes
 bool vote(int voter, int rank, string name);
 void tabulate(void);
 bool print_winner(void);
 int find_min(void);
 bool is_tie(int min);
 void eliminate(int min);

 int main(int argc, string argv[])
 {
    // Check for invalid usage
    if (argc < 2)
    {
        printf("Usage: runoff [candidate ...]\n");
        return 1;
    }

    // Populate array of candidates
    candidate_count = argc - 1;
    if (candidate_count > MAX_CANDIDATES)
    {
        printf("Maximum number of candidates is %i\n", MAX_CANDIDATES);
        return 2;
    }
    for (int i = 0; i < candidate_count; i++)
    {
        candidates[i].name = argv[i + 1];
        candidates[i].votes = 0;
        candidates[i].eliminated = false;
    }

    voter_count = get_int("Number of voters: ");
    if (voter_count > MAX_VOTERS)
    {
        printf("Maximum number of voters is %i\n", MAX_VOTERS);
        return 3;
    }

    // Keep querying for votes
    for (int i = 0; i < voter_count; i++)
    {

        // Query for each rank
        for (int j = 0; j < candidate_count; j++)
        {
            string name = get_string("Rank %i: ", j + 1);

            // Record vote, unless it's invalid
            if (!vote(i, j, name))
            {
                printf("Invalid vote.\n");
                return 4;
            }
        }

        printf("\n");
    }

    // Keep holding runoffs until winner exists
    while (true)
    {
        // Calculate votes given remaining candidates
        tabulate();

        // Check if election has been won
        bool won = print_winner();
        if (won)
        {
            break;
        }

        // Eliminate last-place candidates
        int min = find_min();
        bool tie = is_tie(min);

        // If tie, everyone wins
        if (tie)
        {
            for (int i = 0; i < candidate_count; i++)
            {
                if (!candidates[i].eliminated)
                {
                    printf("%s\n", candidates[i].name);
                }
            }
            break;
        }

        // Eliminate anyone with minimum number of votes
        eliminate(min);

        // Reset vote counts back to zero
        for (int i = 0; i < candidate_count; i++)
        {
            candidates[i].votes = 0;
        }
    }
    return 0;
 }

 // Record preference if vote is valid
 bool vote(int voter, int rank, string name)
 {
    // iterate through candidates based on candidate_count
    for (int i = 0; i < candidate_count; i++)
    {
        // check if name matches candidates name
        if (strcmp(candidates[i].name, name) == 0)
        {
            // record preference
            preferences[voter][rank] = i;
            return true;
        }
    }

    return false;
 }

 // Tabulate votes for non-eliminated candidates
 void tabulate(void)
 {
    // iterate by the number of voters
    for (int i = 0; i < voter_count; i++)
    {
        // for each voter iterate by the number of candidates
        for (int j = 0; j < candidate_count; j++)
        {
            // if the candidate isnt eliminated yet
            if (!candidates[preferences[i][j]].eliminated)
            {
                // add to their votes
                candidates[preferences[i][j]].votes++;
                break;
            }
        }
    }

    return;
 }

 // Print the winner of the election, if there is one
 bool print_winner(void)
 {
    // iterate based on the number of candidates
    for (int i = 0; i < candidate_count; i++)
    {
        // if candidates votes/voter count are greater than 50 they are the winner
        if (((candidates[i].votes / voter_count) * 100) > 50)
        {
            printf("%s\n", candidates[i].name);
            return true;
        }
    }

    // for (int i = 0; i < candidate_count; i++)
    // {
    //     printf("c: %s, v: %i, e: %d\n", candidates[i].name, candidates[i].votes, candidates[i].eliminated);
    // }

    return false;
 }

 // Return the minimum number of votes any remaining candidate has
 int find_min(void)
 {
    // start off with the number of voters we have and reduce
    int min = voter_count;

    // iterate based on the number of candidates
    for (int i = 0; i < candidate_count; i++)
    {
        // if the candidates has a lower score than min & they are not eliminated
        if (candidates[i].votes < min && !candidates[i].eliminated)
        {
            min = candidates[i].votes;
        }
    }

    return min;
 }

 // Return true if the election is tied between all candidates, false otherwise
 bool is_tie(int min)
 {
    // candidates left
    int c_left = 0;
    // candidates above min left
    int m_left = 0;

    // iterate based on the number of candidates
    for (int i = 0; i < candidate_count - 1; i++)
    {
        // if the candidate hasnt been elimninated add to c_left
        if (!candidates[i].eliminated)
        {
            c_left++;
        }

        // if this candidates votes are the same as min add to m_left
        if (candidates[i].votes == min)
        {
            m_left++;
        }
    }

    // if c_left matches m_left we can say they are all tied
    if (c_left == m_left)
    {
        return true;
    }


    // TODO
    return false;
 }

 // Eliminate the candidate (or candidiates) in last place
 void eliminate(int min)
 {
    // iterate based on the number of candidates
    for (int i = 0; i < candidate_count; i++)
    {
        // if the candidates votes matches min then eliminate them
        if (candidates[i].votes == min)
        {
            candidates[i].eliminated = true;
        }
    }

    // TODO
    return;
 }
	#include <cs50.h>
	#include <stdio.h>
	#include <string.h>

	// Max voters and candidates
	#define MAX_VOTERS 100
	#define MAX_CANDIDATES 9

	// preferences[i][j] is jth preference for voter i
	int preferences[MAX_VOTERS][MAX_CANDIDATES];

	// Candidates have name, vote count, eliminated status
	typedef struct
	{
	string name;
	int votes;
	bool eliminated;
	}
	candidate;

	// Array of candidates
	candidate candidates[MAX_CANDIDATES];

	// Numbers of voters and candidates
	int voter_count;
	int candidate_count;

	// Function prototypes
	bool vote(int voter, int rank, string name);
	void tabulate(void);
	bool print_winner(void);
	int find_min(void);
	bool is_tie(int min);
	void eliminate(int min);

	int main(int argc, string argv[])
	{
	// Check for invalid usage
	if (argc < 2)
	{
	printf("Usage: runoff [candidate ...]\n");
	return 1;
	}

	// Populate array of candidates
	candidate_count = argc - 1;
	if (candidate_count > MAX_CANDIDATES)
	{
	printf("Maximum number of candidates is %i\n", MAX_CANDIDATES);
	return 2;
	}
	for (int i = 0; i < candidate_count; i++)
	{
	candidates[i].name = argv[i + 1];
	candidates[i].votes = 0;
	candidates[i].eliminated = false;
	}

	voter_count = get_int("Number of voters: ");
	if (voter_count > MAX_VOTERS)
	{
	printf("Maximum number of voters is %i\n", MAX_VOTERS);
	return 3;
	}

	// Keep querying for votes
	for (int i = 0; i < voter_count; i++)
	{

	// Query for each rank
	for (int j = 0; j < candidate_count; j++)
	{
	string name = get_string("Rank %i: ", j + 1);

	// Record vote, unless it's invalid
	if (!vote(i, j, name))
	{
	printf("Invalid vote.\n");
	return 4;
	}
	}

	printf("\n");
	}

	// Keep holding runoffs until winner exists
	while (true)
	{
	// Calculate votes given remaining candidates
	tabulate();

	// Check if election has been won
	bool won = print_winner();
	if (won)
	{
	break;
	}

	// Eliminate last-place candidates
	int min = find_min();
	bool tie = is_tie(min);

	// If tie, everyone wins
	if (tie)
	{
	for (int i = 0; i < candidate_count; i++)
	{
	if (!candidates[i].eliminated)
	{
	printf("%s\n", candidates[i].name);
	}
	}
	break;
	}

	// Eliminate anyone with minimum number of votes
	eliminate(min);

	// Reset vote counts back to zero
	for (int i = 0; i < candidate_count; i++)
	{
	candidates[i].votes = 0;
	}
	}
	return 0;
	}

	// Record preference if vote is valid
	bool vote(int voter, int rank, string name)
	{
	// iterate through candidates based on candidate_count
	for (int i = 0; i < candidate_count; i++)
	{
	// check if name matches candidates name
	if (strcmp(candidates[i].name, name) == 0)
	{
	// record preference
	preferences[voter][rank] = i;
	return true;
	}
	}

	return false;
	}

	// Tabulate votes for non-eliminated candidates
	void tabulate(void)
	{
	// iterate by the number of voters
	for (int i = 0; i < voter_count; i++)
	{
	// for each voter iterate by the number of candidates
	for (int j = 0; j < candidate_count; j++)
	{
	// if the candidate isnt eliminated yet
	if (!candidates[preferences[i][j]].eliminated)
	{
	// add to their votes
	candidates[preferences[i][j]].votes++;
	break;
	}
	}
	}

	return;
	}

	// Print the winner of the election, if there is one
	bool print_winner(void)
	{
	// iterate based on the number of candidates
	for (int i = 0; i < candidate_count; i++)
	{
	// if candidates votes/voter count are greater than 50 they are the winner
	if (((candidates[i].votes / voter_count) * 100) > 50)
	{
	printf("%s\n", candidates[i].name);
	return true;
	}
	}

	// for (int i = 0; i < candidate_count; i++)
	// {
	// printf("c: %s, v: %i, e: %d\n", candidates[i].name, candidates[i].votes, candidates[i].eliminated);
	// }

	return false;
	}

	// Return the minimum number of votes any remaining candidate has
	int find_min(void)
	{
	// start off with the number of voters we have and reduce
	int min = voter_count;

	// iterate based on the number of candidates
	for (int i = 0; i < candidate_count; i++)
	{
	// if the candidates has a lower score than min & they are not eliminated
	if (candidates[i].votes < min && !candidates[i].eliminated)
	{
	min = candidates[i].votes;
	}
	}

	return min;
	}

	// Return true if the election is tied between all candidates, false otherwise
	bool is_tie(int min)
	{
	// candidates left
	int c_left = 0;
	// candidates above min left
	int m_left = 0;

	// iterate based on the number of candidates
	for (int i = 0; i < candidate_count - 1; i++)
	{
	// if the candidate hasnt been elimninated add to c_left
	if (!candidates[i].eliminated)
	{
	c_left++;
	}

	// if this candidates votes are the same as min add to m_left
	if (candidates[i].votes == min)
	{
	m_left++;
	}
	}

	// if c_left matches m_left we can say they are all tied
	if (c_left == m_left)
	{
	return true;
	}


	// TODO
	return false;
	}

	// Eliminate the candidate (or candidiates) in last place
	void eliminate(int min)
	{
	// iterate based on the number of candidates
	for (int i = 0; i < candidate_count; i++)
	{
	// if the candidates votes matches min then eliminate them
	if (candidates[i].votes == min)
	{
	candidates[i].eliminated = true;
	}
	}

	// TODO
	return;
	}