1039. Course List for Student (25)

    直接用 string 存储名字会由于C++的 cin, cout IO效率问题导致最后一个case超时，于是改为char数组存储名字，然后Hash为整数，再创建映射。

#include <iostream>#include <cstdio>#include <set>#include <unordered_map>#include <cstring>using namespace std;int Hash(char *name){return (name[0]-'A'+10)*36*36*36 + (name[1]-'A'+10)*36*36 + (name[2]-'A'+10)*36 + (name[3]-'0');}int main(){int n, k;scanf("%d%d", &n, &k);unordered_map<int, set<int>> stus;char name[5];for(int i = 0; i < k; ++i){int index, num;scanf("%d%d", &index, &num);for(int j = 0; j < num; ++j){scanf("%s", name);int val = Hash(name);if(stus.find(val) == stus.end()) stus.insert({val, set<int>()});stus[val].insert(index);}}for(int i = 0; i < n; ++i){scanf("%s", name);int val = Hash(name);printf("%s %d", name, (int)stus[val].size());for(auto& course : stus[val]){printf(" %d", course);}printf("\n");}return 0;}