UVa 12412 - A Typical Homework (a.k.a Shi Xiong Bang Bang Mang)

Accepted date: 2019-04-10
Run Time: 0.000
Ranking (as of 2019-04-10): 310 out of 425
Language: C++11

/*
  UVa 12412 - A Typical Homework (a.k.a Shi Xiong Bang Bang Mang)

  To build using Visual Studio 2015:
    cl -EHsc -O2 UVa_12412_A_Typical_Homework.cpp
*/

#include <vector>
#include <map>
#include <functional>
#include <cstdio>
#include <cstring>
#include <cctype>
using namespace std;

const int sid_chrs = 10, max_cid = 20, max_name_chrs = 10, nr_scores = 4;
const double eps = 1.0e-5;

struct student {
  long long sid;
  int cid;
  char name[max_name_chrs + 1];
  int scores[nr_scores];
  int total, nr_passed;
};

vector<student> students;

struct score {
  int total;
  int nr, nr_passed, nr_failed;
};

struct statistic {
  int overall[nr_scores + 1]; // overall[i] is the number of students who passed i subjects
  score scores[nr_scores];
} statistics[max_cid + 1];

statistic& whole_statistic = statistics[0];

multimap<int, int, greater<int>> total_scores; // key is a total score, value is an index to students[]

void add_students()
{
  while (true) {
    puts("Please enter the SID, CID, name and four scores. Enter 0 to finish.");
    char ssid[sid_chrs + 1];
    scanf("%s", ssid);
    if (!strcmp(ssid, "0"))
      return;
    student s;
    s.sid = strtoll(ssid, nullptr, 10);
    scanf("%d %s %d %d %d %d", &s.cid, s.name, &s.scores[0], &s.scores[1], &s.scores[2], &s.scores[3]);
    size_t i, n = students.size();
    for (i = 0; i < n; i++)
      if (s.sid == students[i].sid)
        break;
    if (i < n) {
      puts("Duplicated SID.");
      continue;
    }
    s.total = 0, s.nr_passed = 0;
    statistic& st = statistics[s.cid];
    for (int i = 0; i < nr_scores; i++) {
      s.total += s.scores[i], st.scores[i].total += s.scores[i], st.scores[i].nr++,
        whole_statistic.scores[i].total += s.scores[i], whole_statistic.scores[i].nr++;;
      if (s.scores[i] >= 60)
        s.nr_passed++, st.scores[i].nr_passed++, whole_statistic.scores[i].nr_passed++;
      else
        st.scores[i].nr_failed++, whole_statistic.scores[i].nr_failed++;
    }
    st.overall[s.nr_passed]++, whole_statistic.overall[s.nr_passed]++;
    students.push_back(s);
    total_scores.insert(make_pair(s.total, n));
  }
}

void remove_student(int si)
{
  student& s = students[si];
  statistic& st = statistics[s.cid];
  for (int i = 0; i < nr_scores; i++) {
    st.scores[i].total -= s.scores[i], st.scores[i].nr--,
      whole_statistic.scores[i].total -= s.scores[i], whole_statistic.scores[i].nr--;
    if (s.scores[i] >= 60)
      st.scores[i].nr_passed--, whole_statistic.scores[i].nr_passed--;
    else
      st.scores[i].nr_failed--, whole_statistic.scores[i].nr_failed--;
  }
  st.overall[s.nr_passed]--, whole_statistic.overall[s.nr_passed]--;
  for (auto j = total_scores.begin(); j != total_scores.end(); ) {
    if (j->second == si)
      total_scores.erase(j++);
    else {
      if (j->second > si)
        j->second--;
      ++j;
    }
  }
}

void remove_students()
{
  while (true) {
    puts("Please enter SID or name. Enter 0 to finish.");
    char sid_or_name[sid_chrs + 1];
    scanf("%s", sid_or_name);
    if (!strcmp(sid_or_name, "0"))
      return;
    int nr_removed = 0;
    if (isdigit(sid_or_name[0])) { // sid
      long long sid = strtoll(sid_or_name, nullptr, 10);
      for (auto i = students.begin(); i != students.end(); ) {
        if (i->sid == sid) {
          remove_student(i - students.begin());
          students.erase(i);
          nr_removed++;
          break;
        }
        else
          ++i;
      }
    }
    else { // name
      for (auto i = students.begin(); i != students.end(); ) {
        if (!strcmp(i->name, sid_or_name)) {
          remove_student(i - students.begin());
          students.erase(i);
          nr_removed++;
        }
        else
          ++i;
      }
    }
    printf("%d student(s) removed.\n", nr_removed);
  }
}

void query_student(int si, int rank)
{
  const student& s = students[si];
  printf("%d %010lld %d %s %d %d %d %d %d %.2lf\n",
    rank, s.sid, s.cid, s.name, s.scores[0], s.scores[1], s.scores[2], s.scores[3],
    s.total, s.total / 4.0 + eps);
}

void query_students()
{
  map<int, int> ranks; // key is an index to students[], value is the rank

  int n = 0, rank = 0, score = -1;
  for (auto i = total_scores.cbegin(); i != total_scores.cend(); i++) {
    n++;
    if (i->first != score) {
      rank = n;
      score = i->first;
    }
    ranks.insert(make_pair(i->second, rank));
  }
  while (true) {
    puts("Please enter SID or name. Enter 0 to finish.");
    char sid_or_name[sid_chrs + 1];
    scanf("%s", sid_or_name);
    if (!strcmp(sid_or_name, "0"))
      return;
    if (isdigit(sid_or_name[0])) { // sid
      long long sid = strtoll(sid_or_name, nullptr, 10);
      for (size_t i = 0, n = students.size(); i < n; i++)
        if (students[i].sid == sid) {
          query_student(i, ranks[i]);
          break;
        }
    }
    else { // name
      for (size_t i = 0, n = students.size(); i < n; i++)
        if (!strcmp(students[i].name, sid_or_name))
          query_student(i, ranks[i]);
    }
  }
}

void show_statistics(void)
{
  const char* courses[nr_scores] = {"Chinese", "Mathematics", "English", "Programming"};
  puts("Please enter class ID, 0 for the whole statistics.");
  int cid;
  scanf("%d", &cid);
  statistic& st = statistics[cid];
  for (int i = 0; i < nr_scores; i++) {
    const score& sc = st.scores[i];
    printf("%s\n", courses[i]);
    printf("Average Score: %.2lf\n", ((sc.nr) ? static_cast<double>(sc.total) / sc.nr : 0.0) + eps);
    printf("Number of passed students: %d\n", sc.nr_passed);
    printf("Number of failed students: %d\n\n", sc.nr_failed);
  }
  int overall = st.overall[4];
  printf("Overall:\nNumber of students who passed all subjects: %d\n", overall);
  overall += st.overall[3];
  printf("Number of students who passed 3 or more subjects: %d\n", overall);
  overall += st.overall[2];
  printf("Number of students who passed 2 or more subjects: %d\n", overall);
  overall += st.overall[1];
  printf("Number of students who passed 1 or more subjects: %d\n", overall);
  printf("Number of students who failed all subjects: %d\n\n", st.overall[0]);
}

#ifdef DEBUG
void print_students()
{
  for (size_t i = 0, n = students.size(); i < n; i++) {
    const student& s = students[i];
    if (s.sid != -1)
      printf("%d: %010lld %d %s %d %d %d %d %d %.2lf\n",
        i, s.sid, s.cid, s.name, s.scores[0], s.scores[1], s.scores[2], s.scores[3],
        s.total, s.total / 4.0 + eps);
  }
  for (auto j = total_scores.cbegin(); j != total_scores.cend(); ++j)
    printf("%d %d\n", j->first, j->second);
}
#endif

int main()
{
  while (true) {
    puts("Welcome to Student Performance Management System (SPMS).\n\n"
      "1 - Add\n2 - Remove\n3 - Query\n4 - Show ranking\n5 - Show Statistics\n0 - Exit\n");
    int c, sc;
    scanf("%d", &c);
    switch (c) {
    case 0:
      break;
    case 1:
      add_students();
#ifdef DEBUG
      print_students();
#endif
      break;
    case 2:
      remove_students();
#ifdef DEBUG
      print_students();
#endif
      break;
    case 3:
      query_students();
      break;
    case 4:
      puts("Showing the ranklist hurts students' self-esteem. Don't do that.");
      break;
    case 5:
      show_statistics();
      break;
    }
    if (!c)
      break;
  }
  return 0;
}