失分点：

• and the output must be sorted in nondecreasing order of their registration numbers. 成绩相同的时候用准考证号码由小到大排序。

a.score != b.score ? a.score > b.score : a.id < b.id;

• registration number (a 13-digit number) 准考证号固定13位，但是当输入为000000011111时存储之后再打印就是11111了，所以要小心。

printf("%013lld %d %d %d\n",stu[i].id.....);

合格代码：

#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
#define N 30000
typedef struct Stu{
  long long id;
  int score;
  int final_rank;
  int location_number;
  int local_rank;
  Stu(){
    id=0;
    score=0;
    final_rank=0;
    location_number=0;
    local_rank=0;
  }
}Stu;
int locations=0;
int length[N]={0};
bool cmp(Stu a,Stu b){
  return a.score != b.score ? a.score > b.score : a.id < b.id;
}
int main(){
  // freopen("test.txt","r+",stdin);
  scanf("%d",&locations);
  int i,j;
  vector<Stu>stu;
  for(i=0;i<locations;i++){
    scanf("%d",&length[i]);
    vector<Stu>s;
    for(j=0;j<length[i];j++){
      Stu v;
      scanf("%lld %d",&v.id,&v.score);
      v.location_number=i+1;
      s.push_back(v);
    }
    sort(s.begin(),s.end(),cmp);
    s[0].local_rank=1;
    // s[0].location_number=i+1;
    stu.push_back(s[0]);
    for(j=1;j<length[i];j++){
        s[j].local_rank=((s[j].score==s[j-1].score)?s[j-1].local_rank:j+1);
        stu.push_back(s[j]);
    }
  }
  sort(stu.begin(),stu.end(),cmp);
  stu[0].final_rank=1;
  for(i=1;i<stu.size();i++){
    stu[i].final_rank=((stu[i].score==stu[i-1].score)?stu[i-1].final_rank:i+1);
  }
  cout<<stu.size()<<endl;
  for(i=0;i<stu.size();i++){
    printf("%013lld %d %d %d\n",stu[i].id,stu[i].final_rank,stu[i].location_number,stu[i].local_rank);
    // cout<<stu[i].id<<" "<<stu[i].final_rank<<" "<<stu[i].location_number<<" "<<stu[i].local_rank<<endl;
  }
}