CS50 - week 3 - runoff -My code has a issue - c

Question

This is the code I came up with for the print_winner function in the week 3 assignment of cs50, runoff.
this is my print_winner function.
Print_winner
It produces some strange behaviour. When the candidate obtains 100% of votes as rank 1, the code works fine. But any less than that the code just keeps on repeating infinitively. I have to use Ctr + c to stop the execution.
For example - ./runoff aa bb cc
if i give 100% of all the first ranks to "cc", it will print the winner correctly as "cc".
But if I give lets say if i give 2/3 of votes to cc and one vote for another, te codes keeps on looping.
This is my complete code.
#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;
//debug
printf("candidate %d %s \n", i,candidates[i].name);
}
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");
}
//debug -vidu
for (int ss = 0; ss < voter_count; ss++)
{
for (int tt = 0; tt < 3; tt++)
{
printf("voter - %d, rank - %d, candidate no - %d \n" , ss, tt, preferences[ss][tt]);
}
}
// 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 //take all these details and enter them to the grid
int count = 0;
if (voter < voter_count && rank < 3)
{
for (int i = 0; i < candidate_count; i++)
{
//debug
printf("--name - %s,\n--candidate.name - %s \n", name, candidates[i].name);
if (strcmp(name, candidates[i].name) == 0)
{
preferences[voter][rank] = i;
//debug - print
printf("voter - %d, rank - %d, total votes - %d, %s \n", voter, rank, i, candidates[i].name);
count = count + 1;
return true;
break;
}
}
return false;
}
else
{
return false;
}
}
// Tabulate votes for non-eliminated candidates
void tabulate(void)
{
// TODO //take votes from preferences and put it to the candidates
for (int i = 0; i < voter_count; i++)
{
for (int j = 0; j < candidate_count; j++)
{
//check for the index no of preferences first candidate
if (preferences[i][0] == j && candidates[j].eliminated == false)
{
candidates[j].votes = candidates[j].votes + 1;
}
}
}
//debug = print the canditate table
for (int k = 0; k < candidate_count; k++)
{
printf("DEBUG in vote = Candid name - %s, Index no - %d, votes - %d \n",candidates[k].name, k,candidates[k].votes);
}
return;
}
// Print the winner of the election, if there is one
bool print_winner(void)
{
// TODO //If any candidate has more than half of the vote, their name should be printed and the function should return//if not false
//debug = print the canditate table
for (int k = 0; k < candidate_count; k++)
{
printf("DEBUG in print_winner = Candid name - %s, Index no - %d, votes - %d \n",candidates[k].name, k,candidates[k].votes);
}
int kk = 0;
//devide by total and
for (int j=0; j < candidate_count; j++)
{
kk = candidates[j].votes/voter_count * 100;
//debug
printf("candidate %d candidates[j].votes - %d \n", j, candidates[j].votes);
printf("candidate %d kk - %d \n", j, kk);
if (kk > 50)
{
printf("the winner is %s \n", candidates[j].name);
return true;
}
}
return false;
}
// Return the minimum number of votes any remaining candidate has
int find_min(void)
{
// TODO
//bubble sort
for (int step = 0; step < candidate_count; step++)
{
// loop to compare array elements
for (int i = 0; i < (candidate_count - 1); i++)
{
// compare two adjacent elements, change > to < to sort in descending order
if (candidates[i].votes > candidates[i + 1].votes)
{
// swapping occurs if elements are not in the intended order
candidate temp = candidates[i];
candidates[i] = candidates[i + 1];
candidates[i + 1] = temp;
}
}
}
return candidates[0].votes;
}
// Return true if the election is tied between all candidates, false otherwise
bool is_tie(int min)
{
// TODO
for (int i=0; i < candidate_count; i++)
{
if (candidates[i].votes == candidates[i + 1].votes && candidates[i].votes == min && candidates[i].votes == candidates[candidate_count].votes)
{
return true;
}
}
return false;
}
// Eliminate the candidate (or candidates) in last place
void eliminate(int min)
{
// TODO
for (int i=0; i < candidate_count; i++)
{
if (candidates[i].votes == min)
{
candidates[i].eliminated = true;
}
}
return;
}

Answer 1

There may be other issues, but one that jumps out is:
kk = candidates[j].votes/voter_count * 100;
Since both variables on the right hand side are of type int, the division is integer division. Since voter_count is always greater than or equal to candidates[j].votes, the value of kk is always either 0 or 100. To get floating point results, you could use:
kk = ((double)candidates[j].votes / (double)voter_count) * 100;
(Both casts aren't strictly necessary, and neither are the outer parens; that's a stylistic choice.)