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 << "]" << "
";
    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, 1, BUF, stdin);
    return *bg++;
} 

inline int ri(){
    int x = 0, f = 1, c = gc();
    for(; c<48||c>57; f = c=='-'?-1:f, c=gc());
    for(; c>47&&c<58; x = x*10 + c - 48, 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-6;
const LL inf = 0x7fffffff;
const LL infLL = 0x7fffffffffffffffLL;
const LL mod = 1e9 + 7;
const int maxN = 1e4 + 7;
const LL ONE = 1;
const LL evenBits = 0xaaaaaaaaaaaaaaaa;
const LL oddBits = 0x5555555555555555;

MIS courses = {MP(0, "Chinese"), MP(1, "Mathematics"), MP(2, "English"), MP(3, "Programming")};

struct Student{
    int cid, scores[4], tot = 0;
    string sid, name;
    double avg;
};
vector< Student > stu;
MSI id_stu;
int totScores[107], 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).

");
    printf ("1 - Add
");
    printf ("2 - Remove
");
    printf ("3 - Query
");
    printf ("4 - Show ranking
");
    printf ("5 - Show Statistics
");
    printf ("0 - Exit

");
}

void add() {
    string tmp;
    while(cin >> tmp) {
        printf ("Please enter the SID, CID, name and four scores. Enter 0 to finish.
");
        if(tmp == "0") break;
        if(id_stu.find(tmp) != id_stu.end()) {
            Rep(i, 6) cin >> tmp;
            printf ("Duplicated SID.
");
            continue;
        }
        Student t;
        int cnt = 0;
        t.sid = tmp;
        cin >> t.cid >> t.name;
        Rep(i, 4) {
            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.
");
        if(tmp == "0") break;
        VI t; 
        if(isdigit(tmp[0])) {
            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.
", 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.
");
        if(tmp == "0") break;
        VI t; 
        if(isdigit(tmp[0])) {
            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 + 1;
            printf("%d %s %d %s %d %d %d %d %d %.2f
", rank, stu[*i].sid.c_str(), stu[*i].cid, stu[*i].name.c_str(), stu[*i].scores[0], stu[*i].scores[1], stu[*i].scores[2], stu[*i].scores[3], stu[*i].tot, stu[*i].avg + EPS);
        }
    }
}

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

void show_stat() {
    int totS[4] = {0}, len = 0;
    int passed[4] = {0}, failed[4] = {0}, passedN[5] = {0};
    int x;
    printf("Please enter class ID, 0 for the whole statistics.
");
    cin >> x;
    
    foreach(i, id_stu) {
        if(!x || stu[i->sd].cid == x) {
            ++len;
            int cnt = 0;
            Rep(j, 4) {
                totS[j] += stu[i->sd].scores[j];
                if(stu[i->sd].scores[j] >= 60) {
                    ++passed[j];
                    ++cnt;
                }
                else ++failed[j];
            }
            ++passedN[cnt];
        }
    }
    
    Rep(i, 4) {
        printf ("%s
", courses[i].c_str());
        if(len) printf ("Average Score: %.2f
", 1.0 * totS[i] / len + EPS);
        else printf ("Average Score: -nan
");
        printf ("Number of passed students: %d
", passed[i]);
        printf ("Number of failed students: %d
", failed[i]);
        printf ("
");
    }
    printf ("Overall:
");
    printf ("Number of students who passed all subjects: %d
", passedN[4]);
    printf ("Number of students who passed 3 or more subjects: %d
", passedN[4] + passedN[3]);
    printf ("Number of students who passed 2 or more subjects: %d
", passedN[4] + passedN[3] + passedN[2]);
    printf ("Number of students who passed 1 or more subjects: %d
", passedN[4] + passedN[3] + passedN[2] + passedN[1]);
    printf ("Number of students who failed all subjects: %d
", passedN[0]);
    printf ("
");
}

void (*func[5])() = {add, del, query, show_rank, show_stat};

int main(){
    //freopen("MyOutput.txt","w",stdout);
    //freopen("input.txt","r",stdin);
    //INIT();
    int op;
    while(1) {
        printWelcome();
        cin >> op;
        if(op == 0) break;
        func[op - 1]();
    }
    return 0;
}