题目链接如下：

Online Judge

这道题折磨了我很久。最后是用了如何比较两个txt文件内容的细微差别-百度经验

这里介绍的fc 1.txt 2.txt 来比较两个答案的差别，最后查出了bug。用的测试样例是UDebug上的一组大数据：12412 | uDebug

为了比较答案，另外还学到了下面这个很有用的用法。

#define debug#ifdef debugfreopen("0.txt","r",stdin);freopen("1.txt","w",stdout);
#endif#ifdef debugfclose(stdin);fclose(stdout);
#endif

我起先的代码问题出在：一个student被删除后，可以重新加回；但我是用mp[sid]（map）来判断这个student还存不存在，被加回后，起先被删除但仍留在vector中的也变成存在了，造成了vector中有了两个重复的student。所以只能在student的结构体中加入了existed这个判断是否存在的变量。（确切来说，mp[sid]可以判断学生是否存在，若存在，则在vec[mp[sid] - 1]这个位置上；existed判断vector上这个student是否存在。）

我的代码如下：

#include <string>
#include <vector>
#include <map>
#include <iostream>
#include <algorithm>
// #define debugstruct stu{std::string sid;int cid;std::string name;std::vector<int> score = std::vector<int> (4);int rank;int totalScore = 0;int existed = 1;
};struct course{int tot = 0;int passed = 0;int failed = 0;
};int cnt, task;
std::vector<stu> vec, vec1;
std::map<std::string, int> mp;
std::string fourCourse[] = {"Chinese", "Mathematics", "English", "Programming"};void mainmenu(){printf("Welcome to Student Performance Management System (SPMS).\n\n");printf("1 - Add\n2 - Remove\n3 - Query\n4 - Show ranking\n5 - Show Statistics\n0 - Exit\n\n");
}void addStudent(){stu temp;while(1){printf("Please enter the SID, CID, name and four scores. Enter 0 to finish.\n");std::cin >> temp.sid;if(temp.sid == "0"){break;}scanf("%d", &temp.cid);std::cin >> temp.name;temp.totalScore = 0;for(int i = 0; i < 4; ++i){scanf("%d", &temp.score[i]);temp.totalScore += temp.score[i];}if(mp[temp.sid]){printf("Duplicated SID.\n");} else{mp[temp.sid] = ++cnt;vec.push_back(temp);}}
}void removeStudent(){std::string str;while(1){printf("Please enter SID or name. Enter 0 to finish.\n");std::cin >> str;if(str == "0"){break;}int xx = 0;if(mp[str]){vec[mp[str] - 1].existed = 0;mp[str] = 0;xx = 1;} else{for(int i = 0; i < vec.size(); ++i){if(vec[i].existed && vec[i].name == str){++xx;vec[i].existed = 0;mp[vec[i].sid] = 0;}}}printf("%d student(s) removed.\n", xx);}
}bool cmp1(const stu &a, const stu &b){return a.totalScore > b.totalScore;
}bool cmp2(const stu &a, const stu &b){return mp[a.sid] < mp[b.sid];
}void queryStudent(){vec1.clear();for(int i = 0; i < vec.size(); ++i){if(vec[i].existed){vec1.push_back(vec[i]);}}sort(vec1.begin(), vec1.end(), cmp1);vec1[0].rank = 1;for(int i = 1; i < vec1.size(); ++i){if(vec1[i].totalScore == vec1[i - 1].totalScore){vec1[i].rank = vec1[i - 1].rank;} else{vec1[i].rank = i + 1;}}sort(vec1.begin(), vec1.end(), cmp2);std::string str;while(1){printf("Please enter SID or name. Enter 0 to finish.\n");std::cin >> str;if(str == "0"){break;}for(int i = 0; i < vec1.size(); ++i){if(vec1[i].sid == str || vec1[i].name == str){printf("%d %s %d %s %d %d %d %d %d %.2f\n", vec1[i].rank, vec1[i].sid.c_str(), vec1[i].cid,vec1[i].name.c_str(), vec1[i].score[0], vec1[i].score[1], vec1[i].score[2], vec1[i].score[3],vec1[i].totalScore, vec1[i].totalScore / 4.0 + 0.00001);}}}
}void showStatistics(){printf("Please enter class ID, 0 for the whole statistics.\n");int cid;scanf("%d", &cid);course a[4];int tot[5] = {0, 0, 0, 0, 0};int stuNbr = 0;int p = 0;for(int i = 0; i < vec.size(); ++i){if(vec[i].existed && (vec[i].cid == cid || !cid)){stuNbr++;int failNum = 0;for(int j = 0; j < 4; ++j){a[j].tot += vec[i].score[j];if(vec[i].score[j] >= 60){a[j].passed++;} else{a[j].failed++;failNum++;}}tot[failNum]++;}}for(int i = 0; i < 4; ++i){printf("%s\n", fourCourse[i].c_str());printf("Average Score: %.2f\n", stuNbr == 0 ? 0 : a[i].tot * 1.0 / stuNbr + 0.00001);printf("Number of passed students: %d\n", a[i].passed);printf("Number of failed students: %d\n\n", a[i].failed);}p += tot[0];printf("Overall:\nNumber of students who passed all subjects: %d\n", p);for(int i = 1; i <= 3; ++i){p += tot[i];printf("Number of students who passed %d or more subjects: %d\n", 4 - i, p);}printf("Number of students who failed all subjects: %d\n\n", tot[4]);
}int main(){#ifdef debugfreopen("0.txt","r",stdin);freopen("1.txt","w",stdout);#endifcnt = 0;while(1){mainmenu();scanf("%d", &task);if(!task){break;}if(task == 1){addStudent();} else if(task == 2){removeStudent();} else if(task == 3){queryStudent();} else if(task == 4){printf("Showing the ranklist hurts students' self-esteem. Don't do that.\n");} else{showStatistics();}}#ifdef debugfclose(stdin);fclose(stdout);#endifreturn 0;
}