CS50 PSet3 Runoff程序循环异常排查求助(附已解决的可行代码)
CS50 PSet3 Runoff程序循环异常排查求助(附已解决的可行代码)
各位大佬好,我最近在做CS50 2020年的Runoff选举作业(就是实现 runoff投票系统的那道题),结果写出来的代码一直陷入死循环,排查了好久都没找到问题,感觉问题大概率出在main函数之外的辅助函数里,可就是摸不着头绪。
我试过用调试器,但程序一直卡循环,而且调试器里根本看不了结构体和数组里的元素,直接把我调试的路给堵死了,实在没办法来求助大家。
编辑更新:问题已解决!
折腾了半天终于搞定了,下面是可以正常运行的完整代码,给有需要的朋友参考:
#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) { // TODO for(int i = 0; i < candidate_count; i++) { if(strcmp(name,candidates[i].name) == 0) { preferences[voter][rank] = i; return true; } } return false; } // Tabulate votes for non-eliminated candidates void tabulate(void) { // TODO for(int i = 0; i < voter_count; i++) { for(int j = 0; j < candidate_count; j++) { if(candidates[preferences[i][j]].eliminated == false) { candidates[preferences[i][j]].votes += 1; break; } } } 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; } } return false; } // Return the minimum number of votes any remaining candidate has int find_min(void) { // TODO int min = 0; for(int i = 0; i < candidate_count; i++) { if(candidates[i].eliminated == false) { if(min >= candidates[i].votes) { min = candidates[i].votes; } } } return min; } // 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].eliminated == false && candidates[i].votes != min) { return false; } } return true; } // Eliminate the candidate (or candidates) in last place void eliminate(int min) { // TODO for(int i = 0; i < candidate_count; i++) { if(!candidates[i].eliminated) { if(candidates[i].votes == min) { candidates[i].eliminated = true; } } } return; }
备注:内容来源于stack exchange,提问作者Hashim
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