UVaOJ 12412 - A Typical Homework

问题描述

解法一：模拟

对于初学者来说是比较繁琐的一道大模拟题，仅写了 C++ 实现，注意事项：

我的实现中用数组来存储 4 门课程的相关统计信息，方便写成循环形式；
我的实现中没有每次在更新数据后做“排序”操作，而是每次查询即时计算 rank;
原题输出样例中的 ` 符号有误，应当是 ' 符号（代码中用注释进行了说明）。

感觉这道题确实适合作为 C++ 语言课程设计大作业，但是作为算法竞赛题有些迷。

#include <bits/stdc++.h>

using namespace std;

struct Student {
  string SID;  // Student ID
  string CID;  // Class ID
  string name;
  int score[4];  // "Chinese", "Mathematics", "English", "Programming"
  int total_score;
  float average_score;
};

vector<Student> database;

void show_menu() {
  cout << "Welcome to Student Performance Management System (SPMS)." << endl
       << endl
       << "1 - Add" << endl
       << "2 - Remove" << endl
       << "3 - Query" << endl
       << "4 - Show ranking" << endl
       << "5 - Show Statistics" << endl
       << "0 - Exit" << endl
       << endl;
}

void do_add() {
  Student tmp;
  while (cout << "Please enter the SID, CID, name and four scores. "
              << "Enter 0 to finish." << endl &&
         cin >> tmp.SID && tmp.SID != "0") {
    cin >> tmp.CID >> tmp.name >> tmp.score[0] >> tmp.score[1] >>
        tmp.score[2] >> tmp.score[3];
    tmp.total_score = tmp.score[0] + tmp.score[1] + tmp.score[2] + tmp.score[3];
    tmp.average_score = 1.0 * tmp.total_score / 4 + 1e-5;
    bool duplicated = false;
    for (auto item : database) {
      if (tmp.SID == item.SID) {
        cout << "Duplicated SID." << endl;
        duplicated = true;
      }
    }
    if (!duplicated) database.push_back(tmp);
  }
}

void do_remove() {
  string target;
  while (cout << "Please enter SID or name. Enter 0 to finish." << endl &&
         cin >> target && target != "0") {
    int cnt = 0;
    for (auto it = database.begin(); it != database.end();) {
      if (it->SID == target || it->name == target) {
        database.erase(it);
        cnt += 1;
      } else {
        ++it;
      }
    }
    cout << cnt << " student(s) removed." << endl;
  }
}

int find_rank(int total_score) {
  int rank = 1;
  for (auto it = database.begin(); it != database.end(); ++it)
    if (total_score < it->total_score) rank += 1;
  return rank;
}

void do_query() {
  string target;
  while (cout << "Please enter SID or name. Enter 0 to finish." << endl &&
         cin >> target && target != "0")
    for (auto it = database.begin(); it != database.end(); ++it)
      if (it->SID == target || it->name == target)
        cout << find_rank(it->total_score) << " " << it->SID << " " << it->CID
             << " " << it->name << " " << it->score[0] << " " << it->score[1]
             << " " << it->score[2] << " " << it->score[3] << " "
             << it->total_score << " " << it->average_score << endl;
}

void do_show_ranking() {
  cout << "Showing the ranklist hurts students' self-esteem. "
       << "Don't do that." << endl;  // Output example is wrong (fix ’ to ')
}

void do_show_statistics() {
  string target,
      course[4] = {"Chinese", "Mathematics", "English", "Programming"};
  int passed[4] = {0}, failed[4] = {0}, pass_num[5] = {0}, student_cnt = 0;
  float total_score[4] = {0}, average_score[4] = {0};

  cout << "Please enter class ID, 0 for the whole statistics." << endl;
  cin >> target;
  for (auto it = database.begin(); it != database.end(); ++it) {
    if (target == "0" || it->CID == target) {
      student_cnt += 1;
      int pass_cnt = 0;

      for (int i = 0; i < 4; ++i) {
        total_score[i] += it->score[i];
        if (it->score[i] >= 60) {
          passed[i] += 1;
          pass_cnt += 1;
        } else {
          failed[i] += 1;
        }
      }

      pass_num[pass_cnt] += 1;
    }
  }

  for (int i = 0; i < 4; ++i) {
    cout << course[i] << endl
         << "Average Score: " << total_score[i] / student_cnt + 1e-5 << endl
         << "Number of passed students: " << passed[i] << endl
         << "Number of failed students: " << failed[i] << endl
         << endl;
  }

  cout << "Overall:" << endl
       << "Number of students who passed all subjects: " << pass_num[4] << endl
       << "Number of students who passed 3 or more subjects: "
       << pass_num[4] + pass_num[3] << endl
       << "Number of students who passed 2 or more subjects: "
       << pass_num[4] + pass_num[3] + pass_num[2] << endl
       << "Number of students who passed 1 or more subjects: "
       << pass_num[4] + pass_num[3] + pass_num[2] + pass_num[1] << endl
       << "Number of students who failed all subjects: " << pass_num[0] << endl
       << endl;
}

int main() {
  int choice;
  while (true) {
    show_menu();
    cin >> choice;
    cout << fixed << setprecision(2);
    if (!choice) break;
    if (choice == 1) do_add();
    if (choice == 2) do_remove();
    if (choice == 3) do_query();
    if (choice == 4) do_show_ranking();
    if (choice == 5) do_show_statistics();
  }
  return 0;
}

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#include <bits/stdc++.h>

using namespace std;

struct Student {

string SID; // Student ID

string CID; // Class ID

string name;

int score[4]; // "Chinese", "Mathematics", "English", "Programming"

int total_score;

float average_score;

};

vector<Student> database;

void show_menu() {

cout << "Welcome to Student Performance Management System (SPMS)." << endl

<< endl

<< "1 - Add" << endl

<< "2 - Remove" << endl

<< "3 - Query" << endl

<< "4 - Show ranking" << endl

<< "5 - Show Statistics" << endl

<< "0 - Exit" << endl

<< endl;

}

void do_add() {

Student tmp;

while (cout << "Please enter the SID, CID, name and four scores. "

<< "Enter 0 to finish." << endl &&

cin >> tmp.SID && tmp.SID != "0") {

cin >> tmp.CID >> tmp.name >> tmp.score[0] >> tmp.score[1] >>

tmp.score[2] >> tmp.score[3];

tmp.total_score = tmp.score[0] + tmp.score[1] + tmp.score[2] + tmp.score[3];

tmp.average_score = 1.0 * tmp.total_score / 4 + 1e-5;

bool duplicated = false;

for (auto item : database) {

if (tmp.SID == item.SID) {

cout << "Duplicated SID." << endl;

duplicated = true;

}

if (!duplicated) database.push_back(tmp);

}

void do_remove() {

string target;

while (cout << "Please enter SID or name. Enter 0 to finish." << endl &&

cin >> target && target != "0") {

int cnt = 0;

for (auto it = database.begin(); it != database.end();) {

if (it->SID == target || it->name == target) {

database.erase(it);

cnt += 1;

} else {

++it;

}

cout << cnt << " student(s) removed." << endl;

}

int find_rank(int total_score) {

int rank = 1;

for (auto it = database.begin(); it != database.end(); ++it)

if (total_score < it->total_score) rank += 1;

return rank;

}

void do_query() {

string target;

while (cout << "Please enter SID or name. Enter 0 to finish." << endl &&

cin >> target && target != "0")

for (auto it = database.begin(); it != database.end(); ++it)

if (it->SID == target || it->name == target)

cout << find_rank(it->total_score) << " " << it->SID << " " << it->CID

<< " " << it->name << " " << it->score[0] << " " << it->score[1]

<< " " << it->score[2] << " " << it->score[3] << " "

<< it->total_score << " " << it->average_score << endl;

}

void do_show_ranking() {

cout << "Showing the ranklist hurts students' self-esteem. "

<< "Don't do that." << endl; // Output example is wrong (fix ’ to ')

}

void do_show_statistics() {

string target,

course[4] = {"Chinese", "Mathematics", "English", "Programming"};

int passed[4] = {0}, failed[4] = {0}, pass_num[5] = {0}, student_cnt = 0;

float total_score[4] = {0}, average_score[4] = {0};

cout << "Please enter class ID, 0 for the whole statistics." << endl;

cin >> target;

for (auto it = database.begin(); it != database.end(); ++it) {

if (target == "0" || it->CID == target) {

student_cnt += 1;

int pass_cnt = 0;

for (int i = 0; i < 4; ++i) {

total_score[i] += it->score[i];

if (it->score[i] >= 60) {

passed[i] += 1;

pass_cnt += 1;

} else {

failed[i] += 1;

}

pass_num[pass_cnt] += 1;

}

for (int i = 0; i < 4; ++i) {

cout << course[i] << endl

<< "Average Score: " << total_score[i] / student_cnt + 1e-5 << endl

<< "Number of passed students: " << passed[i] << endl

<< "Number of failed students: " << failed[i] << endl

<< endl;

}

cout << "Overall:" << endl

<< "Number of students who passed all subjects: " << pass_num[4] << endl

<< "Number of students who passed 3 or more subjects: "

<< pass_num[4] + pass_num[3] << endl

<< "Number of students who passed 2 or more subjects: "

<< pass_num[4] + pass_num[3] + pass_num[2] << endl

<< "Number of students who passed 1 or more subjects: "

<< pass_num[4] + pass_num[3] + pass_num[2] + pass_num[1] << endl

<< "Number of students who failed all subjects: " << pass_num[0] << endl

<< endl;

}

int main() {

int choice;

while (true) {

show_menu();

cin >> choice;

cout << fixed << setprecision(2);

if (!choice) break;

if (choice == 1) do_add();

if (choice == 2) do_remove();

if (choice == 3) do_query();

if (choice == 4) do_show_ranking();

if (choice == 5) do_show_statistics();

}

return 0;

}

#TODO

#TODO

AOAPC II UVaOJ 字符串