解題區/解題區 - UVa

UVa 12412 - A Typical Homework

contents

  1. 1. Problem
  2. 2. Sample Input
  3. 3. Sample Output
  4. 4. Solution

Problem

寫一個模擬成績登錄系統的程式。

Sample Input

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1
0011223344 1 John 79 98 91 100
0022334455 1 Tom 59 72 60 81
0011223344 2 Alice 100 100 100 100
2423475629 2 John 60 80 30 99
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0022334455
John
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0011223344
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Sample Output

1
略

Solution

純苦工題目。

Try adding 1e-5 to all floating point values as you print them.

難怪會 WA，看到時小夥伴們都傻眼，不過應該也是因為大部分仍然使用 float 輸出，用 double 反而會得到 WA 的例子不在少數。

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// WTF > Try adding 1e-5 to all floating point values as you print them.
#include <stdio.h> 
#include <string.h>
#include <iostream>
#include <vector>
#include <map>
using namespace std;
#define eps 1e-5
class Student {
    public:
    string SID, name;
    int CID, score[4];
    Student(int c, int d[], string a = "", string b = "") {
        SID = a, name = b;
        CID = c;
        for (int i = 0; i < 4; i++)
            score[i] = d[i];
    }
    void print() {
        printf("%s %d %s %d %d %d %d %d %.2lf\n", 
            SID.c_str(), CID, name.c_str(),
                score[0], score[1], score[2], score[3], getTotal(), getAvg());
    }
    int getTotal() {
        return score[0] + score[1] + score[2] + score[3];
    }
    double getAvg() {
        return (score[0] + score[1] + score[2] + score[3]) / 4.0 + eps;
    }
};
class SPMS {
    public:
    map<string, int> R_SID;
    vector<Student> students;
    void printMainMenu() {
        puts("Welcome to Student Performance Management System (SPMS).\n");
        puts("1 - Add\n2 - Remove\n3 - Query\n4 - Show ranking\n5 - Show Statistics\n0 - Exit\n");
    }
    void addStudent() {
        char SID[128], name[128];
        int CID, score[4];
        while (true) {
            puts("Please enter the SID, CID, name and four scores. Enter 0 to finish.");
            scanf("%s", SID);
            if (!strcmp(SID, "0"))
                return;
            scanf("%d %s", &CID, name);
            for (int i = 0; i < 4; i++)	scanf("%d", &score[i]);
            
            if (R_SID[SID]) {
                puts("Duplicated SID.");
            } else {
                R_SID[SID]++;
                Student u(CID, score, SID, name);
                students.push_back(u);
            }
        }
    }
    void removeStudent() {
        char s[128];
        while (true) {
            puts("Please enter SID or name. Enter 0 to finish.");
            scanf("%s", s);
            if (!strcmp(s, "0"))
                return;
            int cnt = 0;
            for (vector<Student>::iterator it = students.begin();
                it != students.end(); ) {
                if (it->SID == s || it->name == s) {
                    cnt++;
                    R_SID[it->SID]--;
                    it = students.erase(it);
                } else {
                    it++;
                }
            }
            printf("%d student(s) removed.\n", cnt);
        }
    }
    int getRank(Student u) {
        int ret = 1;
        for (int i = 0; i < students.size(); i++)
            if (students[i].getTotal() > u.getTotal())
                ret++;
        return ret;
    }
    void queryStudent() {
        char s[128];
        while (true) {
            puts("Please enter SID or name. Enter 0 to finish.");
            scanf("%s", s);
            if (!strcmp(s, "0"))
                return;
            for (vector<Student>::iterator it = students.begin();
                it != students.end(); it++) {
                if (it->SID == s || it->name == s) {
                    printf("%d ", getRank(*it));
                    it->print();
                }
            }
        }
    }
    void printRankList() {
        puts("Showing the ranklist hurts students' self-esteem. Don't do that.");
    }
    void printStatistics() {
        puts("Please enter class ID, 0 for the whole statistics.");
        int CID;
        scanf("%d", &CID);
        
        int pass[4] = {}, fail[4] = {}; // subject
        int sum[4] = {}, n = 0;
        int sumtable[5] = {};
        vector<int> table; // student
        table.resize(students.size(), 0); 
        for (int i = 0; i < students.size(); i++) {
            if (CID && CID != students[i].CID)
                continue;
            n++;
            for (int j = 0; j < 4; j++) {
                sum[j] += students[i].score[j];
                if (students[i].score[j] >= 60) {
                    pass[j]++;
                    table[i]++;
                } else {
                    fail[j]++;
                }
            }
            sumtable[table[i]]++;
        }
        
        for (int i = 3; i >= 1; i--)
            sumtable[i] += sumtable[i+1];
        printf("Chinese\nAverage Score: %.2lf\nNumber of passed students: %d\nNumber of failed students: %d\n\n",
            (double) sum[0] / n + eps, pass[0], fail[0]);
        printf("Mathematics\nAverage Score: %.2lf\nNumber of passed students: %d\nNumber of failed students: %d\n\n",
            (double) sum[1] / n + eps, pass[1], fail[1]);
        printf("English\nAverage Score: %.2lf\nNumber of passed students: %d\nNumber of failed students: %d\n\n",
            (double) sum[2] / n + eps, pass[2], fail[2]);
        printf("Programming\nAverage Score: %.2lf\nNumber of passed students: %d\nNumber of failed students: %d\n\n",
            (double) sum[3] / n + eps, pass[3], fail[3]);
        printf("Overall:\nNumber of students who passed all subjects: %d\nNumber of students who passed 3 or more subjects: %d\nNumber of students who passed 2 or more subjects: %d\nNumber of students who passed 1 or more subjects: %d\nNumber of students who failed all subjects: %d\n\n",
            sumtable[4], sumtable[3], sumtable[2], sumtable[1], sumtable[0]);
    }
} spms;
int main() {
    int cmd;
    while (true) {
        spms.printMainMenu();	
        scanf("%d", &cmd);
        if (cmd == 0)
            return 0;
        if (cmd == 1)
            spms.addStudent();
        if (cmd == 2)
            spms.removeStudent();
        if (cmd == 3)
            spms.queryStudent();
        if (cmd == 4)
            spms.printRankList();
        if (cmd == 5)
            spms.printStatistics();
    }	
    return 0;
}
/*
1
0011223344 1 John 79 98 91 100
0022334455 1 Tom 59 72 60 81
0011223344 2 Alice 100 100 100 100
2423475629 2 John 60 80 30 99
0
3
0022334455
John
0
5
1
2
*/