1012. The Best Rank (25)

#include<stdio.h>

typedef struct tagStudent
{
char id[7];
int grades[4];  //acme
int ranks[4];  //acme
}Student;

typedef int (*CmpFun)(const void *a,const void *b);

int cmpa(const void *a ,const void *b)
{
Student* sa = (Student*)a;
Student* sb = (Student*)b;
return sb->grades[0] - sa->grades[0];
}

int cmpc(const void *a ,const void *b)
{
Student* sa = (Student*)a;
Student* sb = (Student*)b;
return sb->grades[1] - sa->grades[1];
}

int cmpm(const void *a ,const void *b)
{
Student* sa = (Student*)a;
Student* sb = (Student*)b;
return sb->grades[2] - sa->grades[2];
}
int cmpe(const void *a ,const void *b)
{
Student* sa = (Student*)a;
Student* sb = (Student*)b;
return sb->grades[3] - sa->grades[3];
}

int cmpid(const void *a ,const void *b)
{
Student* sa = (Student*)a;
Student* sb = (Student*)b;
return strcmp(sa->id,sb->id);
}

int bsearch(Student stu[],int begin,int end,char* target)
{
while(begin<=end)
{
int middle = begin+(end-begin)/2;
int flag = strcmp(stu[middle].id,target);
if(flag==0)
return middle;
else if(flag==1)
end = middle - 1;
else
begin = middle + 1;

}
return -1;
}

char map[] = {'A','C','M','E'};
CmpFun cmps[] = {cmpa,cmpc,cmpm,cmpe};

int main()
{
int n,m;
int i,j;

Student stu[2000];
char ids[2000][7];
int prevgrade;

scanf("%d %d",&n,&m);
for(i=0;i<n;i++)
{
scanf("%s %d %d %d",stu[i].id,&stu[i].grades[1],&stu[i].grades[2],&stu[i].grades[3]);
stu[i].grades[0]= (stu[i].grades[1]+stu[i].grades[2]+stu[i].grades[3])/3;
}
for(i=0;i<m;i++)
scanf("%s",ids[i]);

for(i=0;i<4;i++)
{
prevgrade = -1;
qsort(stu,n,sizeof(Student),cmps[i]);
for(j=0;j<n;j++)
{
if(stu[j].grades[i]!=prevgrade)
{
stu[j].ranks[i] = j+1;
prevgrade = stu[j].grades[i];
}
else
stu[j].ranks[i] = stu[j-1].ranks[i];
}
}

qsort(stu,n,sizeof(Student),cmpid);
for(i=0;i<m;i++)
{
int pos = bsearch(stu,0,n-1,ids[i]);
if(pos==-1)
printf("N/A\n");
else
{
int rank_kind = 0;
for(j=1;j<4;j++)
{
if(stu[pos].ranks[j]<stu[pos].ranks[rank_kind])
rank_kind = j;
}
printf("%d %c\n",stu[pos].ranks[rank_kind],map[rank_kind]);
}
}
return 0;
}