1408201651-hd-GPA.cpp

GPA
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 3341 Accepted Submission(s): 1354
 
Problem Description
Each course grade is one of the following five letters: A, B, C, D, and F. (Note that there is no grade E.) The grade A indicates superior achievement , whereas F stands for failure. In order to calculate the GPA, the letter grades A, B, C, D, and F are assigned the following grade points, respectively: 4, 3, 2, 1, and 0.
 
Input
The input file will contain data for one or more test cases, one test case per line. On each line there will be one or more upper case letters, separated by blank spaces.
 
Output
Each line of input will result in exactly one line of output. If all upper case letters on a particular line of input came from the set {A, B, C, D, F} then the output will consist of the GPA, displayed with a precision of two decimal places. Otherwise, the message "Unknown letter grade in input"will be printed.
 
Sample Input

A B C D F
B F F C C A
D C E F

 
Sample Output

2.00
1.83
Unknown letter grade in input

 
テーマの大意
      学生の成績を表す一連の大文字をあげます.A=4,B=3,C=2,D=1,F=0.この学生の平均点数を出力し,{'A','B','C','D','F'}に属さない大文字が現れると,Unknown letter grade in inputを出力する.
 
エラーの原因
       最初はその5つの大文字以外に「E」しか現れないと思っていたが、それが間違いを招いた.
 
問題を解く構想.
       大文字を与える回数が分からないので、gets()で文字列を入力するしかありません.それから'(スペース)について別途考えます.
 
コード#コード#

<span style="font-size:18px;">#include<stdio.h>
#include<string.h>
char s[1000];
int in(char a)
{
    if(a=='A')
        return 4;
    else if(a=='B')
        return 3;
    else if(a=='C')
        return 2;
    else if(a=='D')
        return 1;
    else if(a=='F')
        return 0;
    else if(a==' ')
        return 5;
    else
        return -1;
    //            (A、B、C、D、E、F、G、H...) 
}
int main()
{
    int i,j,k,l,sum;
    int len;
    while(gets(s)!=NULL)
    {
        len=strlen(s);
        sum=0;
        k=0;
        l=0;
        for(i=0;i<len;i++)
        {
            j=in(s[i]);
            if(j>-1&&j<5)
            {
                sum+=j;
                l++;
            }
            else if(j==-1)
            {
                k=1;
                break;
            }
        }
        if(k==1)
            printf("Unknown letter grade in input
");
        else
            printf("%.2lf
",sum/(l*1.0));
    }
    return 0;
}
</span>