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

是道例题，编写个管理系统，类似于课本十二章的那个。自己写的代码运行样例正常，但提交WA。而且给了一半的代码，就又上网搜了例题原版代码。对比了输入与输出，一直没找到错，目测是有个地方格式错了或者精度控制出现了问题。。 照着重敲一遍Ac了。。

PS：发现问题了，原本写的代码缓冲区出现了问题导致WA。。

#include<stdio.h>
#include<string.h>
#define maxn 1000
#define maxl 100
#define EPS 1e-5
int n;
char sid[maxn][maxl];
int cid[maxn];
char name[maxn][maxl];
int score[maxn][5];
int removed[maxn];
const char* course_name[]={"Chinese","Mathematics","English","Programming"};
int valid(int k)
{
    for (int i=0;i<k;i++)
        if(!removed[i])
            if(!strcmp(sid[i],sid[k]))
                return 0;
    return 1;
}
void add()
{
    while(1)
    {
        printf("Please enter the SID, CID, name and four scores. Enter 0 to finish.\n");
        scanf("%s",sid[n]);
        if(!strcmp(sid[n],"0"))
            break;
        scanf("%d%s%d%d%d%d",&cid[n],name[n],&score[n][0],&score[n][1],&score[n][2],&score[n][3]);
        if(valid(n))
        {
            score[n][4]=score[n][0]+score[n][1]+score[n][2]+score[n][3];
            n++;
        }
        else
            printf("Duplicated SID.\n");
    }
}
int rank(int k)
{
    int r=0;
    for(int i=0;i<n;i++)
        if(!removed[i]&&score[i][4]>score[k][4])
            r++;
    return r+1;
}
void DQ (int isq)
{
    char s[maxl];
    while(1)
    {
        printf("Please enter SID or name. Enter 0 to finish.\n");
        scanf("%s",s);
        if(!strcmp (s, "0"))
            break;
        int r=0;
        for(int i=0;i<n;i++)
            if(!removed[i])
            {
                if(!strcmp(sid[i],s)||!strcmp(name[i],s))
                {
                    if(isq)
                        printf("%d %s %d %s %d %d %d %d %d %.2f\n",rank(i),sid[i],cid[i],name[i],score[i][0],score[i][1],score[i][2],score[i][3],score[i][4],score[i][4]/4.0+EPS);
                    else
                    {
                        removed[i]=1;
                        r++;
                    }
                }
            }
        if(!isq)
            printf("%d student(s) removed.\n",r);
    }
}
double get_course_stat(int c,int s,int* passed,int* failed)
{
    int tot=0;
    *passed=*failed=0;
    for(int i=0;i<n;i++)
        if(!removed[i]&&(!c||cid[i]==c))
        {
            tot+=score[i][s];
            if(score[i][s]>=60)
                (*passed)++;
            else
                (*failed)++;
        }
    return (double)tot/(double)(*passed+*failed);
}
void get_overall_stat(int c,int* cnt)
{
    cnt[0]=cnt[1]=cnt[2]=cnt[3]=cnt[4]=0;
    for(int i=0;i<n;i++)
        if(!removed[i]&&(!c||cid[i]==c))
        {
            int k=0;
            for(int j=0;j<4;j++)
                if(score[i][j]>=60)
                    k++;
            cnt[k]++;
        }
}
void stat()
{
    int c;
    printf("Please enter class ID, 0 for the whole statistics.\n");
    scanf("%d", &c);
    for(int i=0;i<4;i++)
    {
        int passed,failed;
        double avg=get_course_stat(c,i,&passed,&failed);
        printf("%s\n",course_name[i]);
        printf("Average Score: %.2f\n",avg+EPS);
        printf("Number of passed students: %d\n",passed);
        printf("Number of failed students: %d\n",failed);
        printf("\n");
    }
    int cnt[5];
    get_overall_stat(c,cnt);
    printf("Overall:\n");
    printf("Number of students who passed all subjects: %d\n",cnt[4]);
    printf("Number of students who passed 3 or more subjects: %d\n",cnt[4]+cnt[3]);
    printf("Number of students who passed 2 or more subjects: %d\n",cnt[4]+cnt[3]+cnt[2]);
    printf("Number of students who passed 1 or more subjects: %d\n",cnt[4]+cnt[3]+cnt[2]+cnt[1]);
    printf("Number of students who failed all subjects: %d\n",cnt[0]);
    printf("\n");
}
int main()
{
    while(1)
    {
        int choice;
        printf("Welcome to Student Performance Management System (SPMS).\n");
        printf("\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");
        printf("\n");
        scanf("%d",&choice);
        if(choice==0)
            break;
        if(choice==1)
            add();
        if(choice==2)
            DQ(0);
        if(choice==3)
            DQ(1);
        if(choice==4)
            printf("Showing the ranklist hurts students' self-esteem. Don't do that.\n");
        if(choice==5)
            stat();
    }
    return 0;
}