I've completed my print_winner function. It prints the winner but when I run check50 it shows me this error
:( print_winner prints winner of election when some pairs are tied
print_winner did not print winner of election
I am confused because in 'Specification' it was told "You may assume there will not be more than one source.". If I understood this correct, it means that there is only one winner.
Problem description provided here
Here is my full code
#include <cs50.h>
#include <stdio.h>
#include <string.h>
// Max number of candidates
#define MAX 9
// preferences[i][j] is number of voters who prefer i over j
int preferences[MAX][MAX];
// locked[i][j] means i is locked in over j
bool locked[MAX][MAX];
// Each pair has a winner, loser
typedef struct
{
int winner;
int loser;
}
pair;
// Array of candidates
string candidates[MAX];
pair pairs[MAX * (MAX - 1) / 2];
int pair_count;
int candidate_count;
// Function prototypes
bool vote(int rank, string name, int ranks[]);
void record_preferences(int ranks[]);
void add_pairs(void);
void sort_pairs(void);
void lock_pairs(void);
void print_winner(void);
int sequence(int loser, int first_winner);
int main(int argc, string argv[])
{
// Check for invalid usage
if (argc < 2)
{
printf("Usage: tideman [candidate ...]\n");
return 1;
}
// Populate array of candidates
candidate_count = argc - 1;
if (candidate_count > MAX)
{
printf("Maximum number of candidates is %i\n", MAX);
return 2;
}
for (int i = 0; i < candidate_count; i++)
{
candidates[i] = argv[i + 1];
}
// Clear graph of locked in pairs
for (int i = 0; i < candidate_count; i++)
{
for (int j = 0; j < candidate_count; j++)
{
locked[i][j] = false;
}
}
pair_count = 0;
int voter_count = get_int("Number of voters: ");
// Query for votes
for (int i = 0; i < voter_count; i++)
{
// ranks[i] is voter's ith preference
int ranks[candidate_count];
// Query for each rank
for (int j = 0; j < candidate_count; j++)
{
string name = get_string("Rank %i: ", j + 1);
if (!vote(j, name, ranks))
{
printf("Invalid vote.\n");
return 3;
}
}
record_preferences(ranks);
printf("\n");
}
add_pairs();
sort_pairs();
lock_pairs();
print_winner();
return 0;
}
// Update ranks given a new vote
bool vote(int rank, string name, int ranks[])
{
for (int i = 0; i < candidate_count; i++)
{
if (strcmp(name, candidates[i]) == 0)
{
ranks[rank] = i;
return true;
}
}
return false;
}
// Update preferences given one voter's ranks
void record_preferences(int ranks[])
{
// TODO
for (int i = 0; i < candidate_count; i++)
{
for (int j = i + 1; j < candidate_count; j++)
{
preferences[ranks[i]][ranks[j]]++;
}
}
return;
}
// Record pairs of candidates where one is preferred over the other
void add_pairs(void)
{
// TODO
for (int j = 0; j < candidate_count; j++)
{
for (int k = j + 1; k < candidate_count; k++)
{
if (preferences[j][k] > preferences[k][j])
{
pairs[pair_count].winner = j;
pairs[pair_count].loser = k;
pair_count++;
}
else if (preferences[k][j] > preferences[j][k])
{
pairs[pair_count].winner = k;
pairs[pair_count].loser = j;
pair_count++;
}
}
}
return;
}
// Sort pairs in decreasing order by strength of victory
void sort_pairs(void)
{
// TODO
for (int j = 0; j < pair_count - 1; j++)
{
int shifts = 0;
for (int i = 0; i < pair_count - 1 - j; i++)
{
if (preferences[pairs[i].winner][pairs[i].loser] < preferences[pairs[i + 1].winner][pairs[i + 1].loser])
{
pair variable;
variable.winner = pairs[i].winner;
variable.loser = pairs[i].loser;
pairs[i].winner = pairs[i + 1].winner;
pairs[i].loser = pairs[i + 1].loser;
pairs[i + 1].winner = variable.winner;
pairs[i + 1].loser = variable.loser;
shifts++;
}
}
if (shifts == 0)
{
break;
}
}
return;
}
int sequence(int loser, int first_winner)
{
// Count of locks to first winner
int lock = 0;
// Count of wins of the loser
int count = 0;
for (int i = 0; i < candidate_count; i++)
{
if (locked[loser][i] == true)
{
count++;
}
}
// Base case 1, if loser won first winner
if (loser == first_winner)
{
lock++;
return lock;
}
// Base case 2, if loser didn't win anyblode
if (count == 0)
{
return lock;
}
for (int i = 0; i < candidate_count; i++)
{
// If loser won anybody
if (locked[loser][i] == true)
{
// If in this recursive sequence first winner was defeated
if (sequence(i, first_winner) != 0)
{
return 1;
}
}
}
// If first winner was not defeated
return 0;
}
// Lock pairs into the candidate graph in order, without creating cycles
void lock_pairs(void)
{
//
for (int i = 0; i < pair_count; i++)
{
if (sequence(pairs[i].loser, pairs[i].winner) == 0)
{
locked[pairs[i].winner][pairs[i].loser] = true;
}
}
return;
}
// Print the winner of the election
void print_winner(void)
{
// Iterates through all the pairs
for (int i = 0; i < pair_count; i++)
{
int lock = 0;
// Iterates through all the candidates
for (int j = 0; j < candidate_count; j++)
{
// If somebody won the winner of a pair - programm skips whim
if (locked[j][pairs[i].winner] == true)
lock++;
}
// If nobody won the winner of a pair - programm prints his hame and exits
if (lock == 0)
{
printf("%s\n",candidates[pairs[i].winner]);
return;
}
}
return;
}
If I change my print_winner function like this. "Check50" accepts it. However, I can not understand what is the difference between the version of 'print_winner' in the snippet and the version in the full code
void print_winner(void)
{
// Iterates through all the pairs
for (int i = 0; i < candidate_count; i++)
{
int lock = 0;
// Iterates through all the candidates
for (int j = 0; j < candidate_count; j++)
{
// If somebody won the winner of a pair - programm skips whim
if (locked[j][i] == true)
lock++;
}
// If nobody won the winner of a pair - programm prints his hame and exits
if (lock == 0)
{
printf("%s\n",candidates[i]);
return;
}
}
return;
}