Language: C++

#include<iostream>
#include<algorithm>
using namespace std;
char hyakuten(int *students[][3],int n){
  for(int i=0;i<3;i++){
   if(students[n][i]==100)return 'A';
  }
  if((students[n][0]+students[n][1])/2>=90)return 'A';
  if((students[n][0]+students[n][1]+students[n][2])/3>=80)return 'A';
  if((students[n][0]+students[n][1]+students[n][2])/3>=70)return 'B';
  if((studnets[n][0]+studnets[n][1]+students[n][2])/3>=50&&students[n][0]>=80||students[n][1]>=80)return 'B';
  return 'C';
}


int main(){
  int n;
  while(cin>>n&&n){
    int students[10000][3];
    for(int i=0;i<n;i++){
      for(int j=0;j<3;j++){
        cin>>students[i][j];
      }
    }
    for(int i=0;i<n;i++){
      cout<<hyakuten(i)<<endl;
    }
  }
  return 0;
}

Compiler output:
a.cc: In function 'char hyakuten(int* (*)[3], int)':
a.cc:6:21: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
    6 |    if(students[n][i]==100)return 'A';
      |       ~~~~~~~~~~~~~~^~~~~
a.cc:8:21: error: invalid operands of types 'int*' and 'int*' to binary 'operator+'
    8 |   if((students[n][0]+students[n][1])/2>=90)return 'A';
      |       ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
      |                    |              |
      |                    int*           int*
a.cc:9:21: error: invalid operands of types 'int*' and 'int*' to binary 'operator+'
    9 |   if((students[n][0]+students[n][1]+students[n][2])/3>=80)return 'A';
      |       ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
      |                    |              |
      |                    int*           int*
a.cc:10:21: error: invalid operands of types 'int*' and 'int*' to binary 'operator+'
   10 |   if((students[n][0]+students[n][1]+students[n][2])/3>=70)return 'B';
      |       ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
      |                    |              |
      |                    int*           int*
a.cc:11:7: error: 'studnets' was not declared in this scope; did you mean 'students'?
   11 |   if((studnets[n][0]+studnets[n][1]+students[n][2])/3>=50&&students[n][0]>=80||students[n][1]>=80)return 'B';
      |       ^~~~~~~~
      |       students
a.cc:11:74: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
   11 |   if((studnets[n][0]+studnets[n][1]+students[n][2])/3>=50&&students[n][0]>=80||students[n][1]>=80)return 'B';
      |                                                            ~~~~~~~~~~~~~~^~~~
a.cc:11:94: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
   11 |   if((studnets[n][0]+studnets[n][1]+students[n][2])/3>=50&&students[n][0]>=80||students[n][1]>=80)return 'B';
      |                                                                                ~~~~~~~~~~~~~~^~~~
a.cc: In function 'int main()':
a.cc:26:22: error: invalid conversion from 'int' to 'int* (*)[3]' [-fpermissive]
   26 |       cout<<hyakuten(i)<<endl;
      |                      ^
      |                      |
      |                      int
a.cc:26:21: error: too few arguments to function 'char hyakuten(int* (*)[3], int)'
   26 |       cout<<hyakuten(i)<<endl;
      |             ~~~~~~~~^~~
a.cc:4:6: note: declared here
    4 | char hyakuten(int *students[][3],int n){
      |      ^~~~~~~~