大半个月没做题，手非常生...

#include <cstdio>
#include <vector>
#include <map>int N, M, K, t, m, n;
std::vector<std::map<int, int>> vec;void similarity(int a, int b){int cnt = 0;for(auto c : vec[a]){if(vec[b].find(c.first) != vec[b].end()){++cnt;}}printf("%.1f%%\n", cnt * 100.0 / (vec[a].size() + vec[b].size() - cnt));
}int main(){scanf("%d", &N);vec.resize(N + 1);for(int i = 1; i <= N; ++i){scanf("%d", &M);for(int j = 0; j < M; ++j){scanf("%d", &t);vec[i][t] = 1;}}scanf("%d", &K);for(int i = 0; i < K; ++i){scanf("%d %d", &m, &n);similarity(m, n);}return 0;
}

题目如下：

Given two sets of integers, the similarity of the sets is defined to be Nc​/Nt​×100%, where Nc​ is the number of distinct common numbers shared by the two sets, and Nt​ is the total number of distinct numbers in the two sets. Your job is to calculate the similarity of any given pair of sets.

Input Specification:

Each input file contains one test case. Each case first gives a positive integer N (≤50) which is the total number of sets. Then N lines follow, each gives a set with a positive M (≤104) and followed by Mintegers in the range [0,109]. After the input of sets, a positive integer K (≤2000) is given, followed by K lines of queries. Each query gives a pair of set numbers (the sets are numbered from 1 to N). All the numbers in a line are separated by a space.

Output Specification:

For each query, print in one line the similarity of the sets, in the percentage form accurate up to 1 decimal place.

Sample Input:

3
3 99 87 101
4 87 101 5 87
7 99 101 18 5 135 18 99
2
1 2
1 3

Sample Output:

50.0%
33.3%