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

题目链接：https://vjudge.net/problem/UVA-12412

题目大意

　　略。

分析

　　比较大规模的模拟，注意输入输出，浮点数精度，还有排名相同的输出顺序，还有一些边界情况处理。

代码如下

 #include <bits/stdc++.h>
 using namespace std;

 #define INIT() ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
 #define Rep(i,n) for (int i = 0; i < (n); ++i)
 #define For(i,s,t) for (int i = (s); i <= (t); ++i)
 #define rFor(i,t,s) for (int i = (t); i >= (s); --i)
 #define ForLL(i, s, t) for (LL i = LL(s); i <= LL(t); ++i)
 #define rForLL(i, t, s) for (LL i = LL(t); i >= LL(s); --i)
 #define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i)
 #define rforeach(i,c) for (__typeof(c.rbegin()) i = c.rbegin(); i != c.rend(); ++i)

 #define pr(x) cout << #x << " = " << x << "  "
 #define prln(x) cout << #x << " = " << x << endl

 #define LOWBIT(x) ((x)&(-x))

 #define ALL(x) x.begin(),x.end()
 #define INS(x) inserter(x,x.begin())

 #define ms0(a) memset(a,0,sizeof(a))
 #define msI(a) memset(a,inf,sizeof(a))
 #define msM(a) memset(a,-1,sizeof(a))

 #define MP make_pair
 #define PB push_back
 #define ft first
 #define sd second

 template<typename T1, typename T2>
 istream &operator>>(istream &in, pair<T1, T2> &p) {
     in >> p.first >> p.second;
     return in;
 }

 template<typename T>
 istream &operator>>(istream &in, vector<T> &v) {
     for (auto &x: v)
         in >> x;
     return in;
 }

 template<typename T1, typename T2>
 ostream &operator<<(ostream &out, const std::pair<T1, T2> &p) {
     out << "[" << p.first << ", " << p.second << "]" << "\n";
     return out;
 }

 inline int gc(){
     static const int BUF = 1e7;
     static char buf[BUF], *bg = buf + BUF, *ed = bg;

     if(bg == ed) fread(bg = buf, , BUF, stdin);
     return *bg++;
 } 

 inline int ri(){
     int x = , f = , c = gc();
     for(; c<||c>; f = c=='-'?-:f, c=gc());
     for(; c>&&c<; x = x* + c - , c=gc());
     return x*f;
 }

 template<class T>
 inline string toString(T x) {
     ostringstream sout;
     sout << x;
     return sout.str();
 }

 typedef long long LL;
 typedef unsigned long long uLL;
 typedef pair< double, double > PDD;
 typedef pair< int, int > PII;
 typedef pair< int, PII > PIPII;
 typedef pair< string, int > PSI;
 typedef pair< int, PSI > PIPSI;
 typedef set< int > SI;
 typedef set< PII > SPII;
 typedef vector< int > VI;
 typedef vector< VI > VVI;
 typedef vector< PII > VPII;
 typedef map< int, int > MII;
 typedef map< int, string > MIS;
 typedef map< int, PII > MIPII;
 typedef map< PII, int > MPIII;
 typedef map< string, int > MSI;
 typedef map< string, string > MSS;
 typedef map< PII, string > MPIIS;
 typedef map< PII, PII > MPIIPII;
 typedef multimap< int, int > MMII;
 typedef multimap< string, int > MMSI;
 //typedef unordered_map< int, int > uMII;
 typedef pair< LL, LL > PLL;
 typedef vector< LL > VL;
 typedef vector< VL > VVL;
 typedef priority_queue< int > PQIMax;
 typedef priority_queue< int, VI, greater< int > > PQIMin;
 const double EPS = 1e-;
 const LL inf = 0x7fffffff;
 const LL infLL = 0x7fffffffffffffffLL;
 const LL mod = 1e9 + ;
 const int maxN = 1e4 + ;
 const LL ONE = ;
 const LL evenBits = 0xaaaaaaaaaaaaaaaa;
 const LL oddBits = 0x5555555555555555;

 MIS courses = {MP(, "Chinese"), MP(, "Mathematics"), MP(, "English"), MP(, "Programming")};

 struct Student{
     int cid, scores[], tot = ;
     string sid, name;
     double avg;
 };
 vector< Student > stu;
 MSI id_stu;
 int totScores[], slen; // 所有学生的分数数组和在籍学生人数 

 void printWelcome() {
     printf ("Welcome to Student Performance Management System (SPMS).\n\n");
     printf ("1 - Add\n");
     printf ("2 - Remove\n");
     printf ("3 - Query\n");
     printf ("4 - Show ranking\n");
     printf ("5 - Show Statistics\n");
     printf ("0 - Exit\n\n");
 }

 void add() {
     string tmp;
     while(cin >> tmp) {
         printf ("Please enter the SID, CID, name and four scores. Enter 0 to finish.\n");
         if(tmp == "") break;
         if(id_stu.find(tmp) != id_stu.end()) {
             Rep(i, ) cin >> tmp;
             printf ("Duplicated SID.\n");
             continue;
         }
         Student t;
         int cnt = ;
         t.sid = tmp;
         cin >> t.cid >> t.name;
         Rep(i, ) {
             cin >> t.scores[i];
             t.tot += t.scores[i];
             t.avg = t.tot / 4.0;
         }
         totScores[slen++] = -t.tot;

         id_stu[tmp] = stu.size();
         stu.PB(t);
     }
 }

 void del() {
     string tmp;
     while(cin >> tmp) {
         printf("Please enter SID or name. Enter 0 to finish.\n");
         if(tmp == "") break;
         VI t;
         if(isdigit(tmp[])) {
             if(id_stu.find(tmp) != id_stu.end()) t.PB(id_stu[tmp]);
         }
         else foreach(i, id_stu) if(tmp == stu[i->sd].name) t.PB(i->sd);
         printf ("%d student(s) removed.\n", t.size());
         foreach(i, t) {
             id_stu.erase(stu[*i].sid);
             --slen;
             Rep(j, slen) {
                 if(totScores[j] == -stu[*i].tot) {
                     swap(totScores[j], totScores[slen]);
                     break;
                 }
             }
         }
     }
 }

 void query() {
     sort(totScores, totScores + slen);
     string tmp;
     while(cin >> tmp) {
         printf("Please enter SID or name. Enter 0 to finish.\n");
         if(tmp == "") break;
         VI t;
         if(isdigit(tmp[])) {
             if(id_stu.find(tmp) != id_stu.end()) t.PB(id_stu[tmp]);
         }
         else foreach(i, id_stu) if(tmp == stu[i->sd].name) t.PB(i->sd);

         sort(ALL(t));
         foreach(i, t) {
             int rank = lower_bound(totScores, totScores + slen, -stu[*i].tot) - totScores + ;
             printf("%d %s %d %s %d %d %d %d %d %.2f\n", rank, stu[*i].sid.c_str(), stu[*i].cid, stu[*i].name.c_str(), stu[*i].scores[], stu[*i].scores[], stu[*i].scores[], stu[*i].scores[], stu[*i].tot, stu[*i].avg + EPS);
         }
     }
 }

 void show_rank() {
     printf("Showing the ranklist hurts students' self-esteem. Don't do that.\n");
 }

 void show_stat() {
     int totS[] = {}, len = ;
     int passed[] = {}, failed[] = {}, passedN[] = {};
     int x;
     printf("Please enter class ID, 0 for the whole statistics.\n");
     cin >> x;

     foreach(i, id_stu) {
         if(!x || stu[i->sd].cid == x) {
             ++len;
             int cnt = ;
             Rep(j, ) {
                 totS[j] += stu[i->sd].scores[j];
                 if(stu[i->sd].scores[j] >= ) {
                     ++passed[j];
                     ++cnt;
                 }
                 else ++failed[j];
             }
             ++passedN[cnt];
         }
     }

     Rep(i, ) {
         printf ("%s\n", courses[i].c_str());
         if(len) printf ("Average Score: %.2f\n", 1.0 * totS[i] / len + EPS);
         else printf ("Average Score: -nan\n");
         printf ("Number of passed students: %d\n", passed[i]);
         printf ("Number of failed students: %d\n", failed[i]);
         printf ("\n");
     }
     printf ("Overall:\n");
     printf ("Number of students who passed all subjects: %d\n", passedN[]);
     printf ("Number of students who passed 3 or more subjects: %d\n", passedN[] + passedN[]);
     printf ("Number of students who passed 2 or more subjects: %d\n", passedN[] + passedN[] + passedN[]);
     printf ("Number of students who passed 1 or more subjects: %d\n", passedN[] + passedN[] + passedN[] + passedN[]);
     printf ("Number of students who failed all subjects: %d\n", passedN[]);
     printf ("\n");
 }

 void (*func[])() = {add, del, query, show_rank, show_stat};

 int main(){
     //freopen("MyOutput.txt","w",stdout);
     //freopen("input.txt","r",stdin);
     //INIT();
     int op;
     while() {
         printWelcome();
         cin >> op;
         if(op == ) break;
         func[op - ]();
     }
     return ;
 }