1047 Student List for Course

#include"iostream"
#include"vector"
#include"unordered_map"
#include"algorithm"
using namespace std;

int main() {
    int n,k,cNum,index;
    scanf("%d%d",&n,&k);
    string name;
    unordered_map<int ,vector<string>> ans;
    for(int i = 0 ; i < n; ++i) {
        cin>>name;
        scanf("%d",&cNum);
        for(int j = 0; j < cNum; ++j) {
            scanf("%d",&index);
            ans[index].push_back(name);
        }
    }
    for(int i = 1; i <= k; ++i) {
        printf("%d %d\n",i,ans[i].size());
        sort(ans[i].begin(),ans[i].end());//对当前vector中的string按字典序排序 
        for(auto it = ans[i].begin(); it != ans[i].end(); ++it)
            printf("%s\n",it->c_str());//string 转char* 输出更快 
    }
    return 0 ;
}