There is this exercise of cs50 that we have to make a runoff election then print the winner when somebody it has more than 50% of all votes. so, to make the election running while the winner can't be found, it has a while loop which always return true until the "print_winner()" function break it. but even when I make the function print_winner and the candidate has more than 50% of votes, the loop doesn't stop.
at first (when the print_winner() function wasn't ready) I tried to look at all my code and see if there is some error, but I can't find it then I realize that I need make the print_winner() function at least, but, even when the function its complete, it doesn't work.
So, I want to know if it's normal because the code isn't all ready or if it's a real bug.
And, if it's a real bug, where should I look to fix it?
Here's the code:
#include <cs50.h>
#include <stdio.h>
#include <string.h>
// Max voters and candidates
#define MAX_VOTERS 100 // constante MAX de eleitores = 100
#define MAX_CANDIDATES 9 // constante MAX de candidatos = 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++) // loop que add os candidatos na array candidate
{
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++) // i ira gerar a quantidade de vezes que o loop j sera iniciado
{
// 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)
{
// TODO
for (int i = 0; i < voter_count; i++) //passa por todos os eleitores
{
if (strcmp(name, candidates[i].name) == 0) // compara os nomes
{
preferences[voter][rank] = i; // preferences[eleitor 0][1° opçao 0] = candidato
return true;
}
}
return false;
}
// Tabulate votes for non-eliminated candidates
void tabulate(void)
{
// TODO
// mede o tamanho da array
int lenght = sizeof(preferences) / sizeof(preferences[0]);
for (int i = 0; i < voter_count; i++)
{
for (int j = 0; j < candidate_count; j++)
{
if (candidates[preferences[i][j]].eliminated == false)
{
break;
}
else if (candidates[preferences[i][j]].eliminated == true)
{
candidates[preferences[i][j + 1]].votes++;
}
}
printf("\n");
}
return;
}
// Print the winner of the election, if there is one
bool print_winner(void)
{
// TODO
for (int i = 0; i < candidate_count; i++)
{
if (candidates[i].votes > (voter_count / 2))
{
printf("%s\n", candidates[i].name);
return true;
break;
}
}
return false;
}
// Return the minimum number of votes any remaining candidate has
int find_min(void)
{
// TODO
return 0;
}
// Return true if the election is tied between all candidates, false otherwise
bool is_tie(int min)
{
// TODO
return false;
}
// Eliminate the candidate (or candidates) in last place
void eliminate(int min)
{
// TODO
return;
}
The infinite loop at that moment was normal because the code wasn't ready yet. The functions find_min, is_Tie, and eliminate needed to be completed for the program to run without any error.
But why? In the previous code, the functions find_min, is_Tie, and eliminate are in a loop that will only be broken if they get a winner. The code can't return a winner when they can't calculate all of the votes, eliminate all of them who don't have more than 50% of all votes, or check if it's a tie.
// 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;
}
}