【发布时间】：2023-03-23 02:06:01
【问题描述】：
我在 Tideman pset3 上遇到了 lock_pair 和 print_winner 问题（此处的上下文：https://cs50.harvard.edu/x/2020/psets/3/tideman/#:~:text=check50%20cs50/problems/2020/x/tideman）。尽我所能进行调试，但我似乎无法跳过创建循环的对。请寻求所有帮助。
:) 潮人.c 存在
:) 潮人编译
:) 给定候选人姓名时投票返回 true
:) 当给定无效候选人的名字时，投票返回 false
:) 投票正确设置了第一偏好的排名
:) 投票正确设置所有偏好的排名
:) record_preferences 正确设置了第一个选民的偏好
:) record_preferences 正确设置了所有选民的偏好
:) add_pairs 在没有关系时生成正确的对数
:) add_pairs 在存在关系时生成正确的对数
:) add_pairs 用获胜对填充对数组
:) add_pairs 不会用丢失的对填充对数组
:) sort_pairs 按胜率对候选对象进行排序
:) lock_pairs 在没有循环时锁定所有对
:( lock_pairs 如果创建循环则跳过最后一个对
lock_pairs did not correctly lock all non-cyclical pairs
:( lock_pairs 如果创建循环则跳过中间对
lock_pairs did not correctly lock all non-cyclical pairs
:( print_winner 在一位候选人胜过所有其他候选人时打印选举获胜者
print_winner did not print winner of election
:( print_winner 打印一些对子并列时的选举获胜者
print_winner did not print winner of election
#include <cs50.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.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 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[])
{
for(int r = 0; r < candidate_count; r++)
{
for(int rc = 0; rc < candidate_count; rc++)
{
if(r < rc)
{
preferences[ranks[r]][ranks[rc]]++;
}
}
}
}
// Record pairs of candidates where one is preferred over the other
void add_pairs(void)
{
for(int row = 0; row < candidate_count; row++)
{
for(int column = 0; column < candidate_count; column++)
{
if(preferences[row][column] > preferences[column][row])
{
pairs[pair_count].winner = row;
pairs[pair_count].loser = column;
pair_count++;
}
}
}
}
// Sort pairs in decreasing order by strength of victory
void sort_pairs(void)
{
int maxindex;
for(int a = 0; a < pair_count - 1; a++)
{
maxindex = a;
int largestdiff = preferences[pairs[a].winner][pairs[a].loser] - preferences[pairs[a].loser][pairs[a].winner];
for(int b = a + 1; b < pair_count; b++)
{
if(preferences[pairs[b].winner][pairs[b].loser] - preferences[pairs[b].loser][pairs[b].winner] > largestdiff)
{
largestdiff = preferences[pairs[b].winner][pairs[b].loser] - preferences[pairs[b].loser][pairs[b].winner];
maxindex = b;
}
}
pair max = pairs[maxindex];
pairs[maxindex] = pairs[a];
pairs[a] = max;
}
}
// Lock pairs into the candidate graph in order, without creating cycles
void lock_pairs(void)
{
//Set everything to false first
for(int row = 0; row < candidate_count; row++)
{
for(int column = 0; column < candidate_count; column++)
{
locked[row][column] = false;
}
}
//Set the first pair to true
locked[pairs[0].winner][pairs[0].loser] = true;
//Iterate each pair and skip if there is a cycle
for(int b = 1; b < pair_count; b++)
{
for(int c = b - 1; c > -1; c--)
{
if(pairs[b].winner == pairs[c].loser)
{
locked[pairs[b].winner][pairs[b].loser] = false;
break;
}
}
locked[pairs[b].winner][pairs[b].loser] = true;
}
}
// Print the winner of the election
void print_winner(void)
{
string winner = candidates[0];
for(int column = 0; column < candidate_count; column++)
{
for(int row = 0; row < candidate_count; row++)
{
if(locked[row][column] == true)
{
winner = candidates[column + 1];
break;
}
else
{
winner = candidates[column];
if(row == candidate_count)
{
break;
}
}
}
}
printf("%s\n", winner);
}
【问题讨论】：
标签： cs50