Uva12412 (implement)

这里有个非常非常注意的点：对于浮点数运算，首先十分推荐用double，然后如果出现浮点数保留几位小数的情况，一定要在执行保留小数前另外加eps（精度容错）

/** 20171104*/#include <cstdio>#include <cstring>using namespace std;#define maxn 10000#define eps 0.00001const char fname[][20] = {"Chinese","Mathematics","English","Programming"};struct Node{    int id;    char num[100];    int cnum;    char name[100];    int g[10];}p[maxn];int cnt = 0;void print_All(){    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");}bool Add(){    printf("Please enter the SID, CID, name and four scores. Enter 0 to finish.\n");    scanf("%s",p[cnt].num);    if(strcmp(p[cnt].num,"0")==0) return false;    scanf("%d %s %d %d %d %d",&p[cnt].cnum,p[cnt].name,&p[cnt].g[0],&p[cnt].g[1],&p[cnt].g[2],&p[cnt].g[3]);    for(int i=0;i<cnt;i++) if(strcmp(p[cnt].num,p[i].num)==0){printf("Duplicated SID.\n");return true;}    p[cnt].id = cnt+1;    cnt++;    return true;}bool Remove(){    printf("Please enter SID or name. Enter 0 to finish.\n");    char numt[100];    scanf("%s",numt);    int ans = 0;    if(strcmp(numt,"0")==0) return false;    for(int i=0;i<cnt;i++)         if(strcmp(p[i].num,numt)==0||strcmp(p[i].name,numt)==0)         {            p[i].id = 0;            memset(p[i].num,0,sizeof(p[i].num));            memset(p[i].name,0,sizeof(p[i].name));            ans++;        }    printf("%d student(s) removed.\n",ans);    return true;}int rank(int k){    int key = 0;    for(int j=0;j<4;j++) key+=p[k].g[j];    int ans = 0;    for(int i=0;i<cnt;i++)    {        if(p[i].id!=0)        {            int res = 0;            for(int j=0;j<4;j++)            {                res+=p[i].g[j];            }            if(res>key) ans++;        }    }    return ans+1;}bool Query(){    printf("Please enter SID or name. Enter 0 to finish.\n");    char numt[100];    scanf("%s",numt);    if(strcmp(numt,"0")==0) return false;    for(int i=0;i<cnt;i++)         if(strcmp(p[i].num,numt)==0||strcmp(p[i].name,numt)==0)             printf("%d %s %d %s %d %d %d %d %d %.2f\n",rank(i),p[i].num,p[i].cnum,p[i].name,p[i].g[0],p[i].g[1],p[i].g[2],p[i].g[3],p[i].g[0]+p[i].g[1]+p[i].g[2]+p[i].g[3],(p[i].g[0]+p[i].g[1]+p[i].g[2]+p[i].g[3])/4.0+eps);    return true;}void ShowRanking(){    printf("Showing the ranklist hurts students' self-esteem. Don't do that.\n");}void ShowStatistics(){    printf("Please enter class ID, 0 for the whole statistics.\n");    int cnumt = 0;    scanf("%d",&cnumt);    for(int i=0;i<4;i++)    {        printf("%s\n",fname[i]);        double ans = 0;        int ansnum = 0;        int passnum = 0;        for(int j=0;j<cnt;j++)             if(p[j].id!=0&&(cnumt==0||cnumt==p[j].cnum))             {                   ans+=p[j].g[i];                 ansnum++;                if(p[j].g[i]>=60) passnum++;            }        printf("Average Score: %.2f\n",ans/ansnum+eps);        printf("Number of passed students: %d\n",passnum);        printf("Number of failed students: %d\n",ansnum-passnum);        printf("\n");    }    int a = 0;    int b = 0;    int c = 0;    int d = 0;    int e = 0;    for(int i=0;i<cnt;i++)    {        if(p[i].id!=0&&(cnumt==0||cnumt==p[i].cnum))        {            int temp = 0;            for(int j=0;j<4;j++)            {                if(p[i].g[j]>=60)                    temp++;            }            if(temp>=4) a++;            else if(temp>=3) b++;            else if(temp>=2) c++;            else if(temp>=1) d++;            else e++;        }    }    printf("Overall:\n");    printf("Number of students who passed all subjects: %d\n",a);    printf("Number of students who passed 3 or more subjects: %d\n",a+b);    printf("Number of students who passed 2 or more subjects: %d\n",a+b+c);    printf("Number of students who passed 1 or more subjects: %d\n",a+b+c+d);    printf("Number of students who failed all subjects: %d\n",e);    printf("\n");}int main(){    //freopen("input.txt","r",stdin);    //freopen("ans.txt","w",stdout);    int a;    print_All();    while(scanf("%d",&a)!=EOF&&a)    {        if(a==1) while(Add());        if(a==2) while(Remove());        if(a==3) while(Query());        if(a==4) ShowRanking();        if(a==5) ShowStatistics();        print_All();    }    return 0;}