哪里有问题

#include<iostream>
#include<cstring>
using namespace std;
struct student
{
    int number;
    int scoreEn;
    int scoreMa;
    int scoreCh;
}stu1[305];
int main()
{
    int i,j,k,n,sum[10001];
    cin>>n;
    for(i=1;i<=n;i++)
    {
    cin>>stu1[i].scoreEn;
    cin>>stu1[i].scoreMa;
    cin>>stu1[i].scoreCh;
    sum[i]=stu1[i].scoreEn+stu1[i].scoreMa+stu1[i].scoreCh;
    } 
    for(i=1;i<=n;i++)
    {
    for(j=i+1;j<=n;j++)
      if(sum[j]>sum[i])
      {
         k=sum[i];sum[i]=sum[j];sum[j]=k;
        k=stu1[i].number;stu1[i].number=stu1[i+1].number;stu1[i+1].number=k;
      }  
      for(i=1;i<=5;i++)
      {
        if(sum[i]=sum[j])
        if(stu1[i].scoreCh>stu1[j].scoreCh)
       {
         k=stu1[i].number;stu1[i].number=stu1[j].number;stu1[j].number=k;
       }
    if(stu1[i].scoreCh=stu1[j].scoreCh)
    continue;
       } 
    for(i=1;i<=5;i++)
    {
    cout<<stu1[i].number;
    cout<<sum[i];
        }
}