PAT A1063 Set Similarity (25分)

题目链接：https://pintia.cn/problem-sets/994805342720868352/problems/994805409175420928

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

输入
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 (≤10^​4​​ ) and followed by M integers in the range [0,10^​9​​ ]. 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.

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

样例输入
3
3 99 87 101
4 87 101 5 87
7 99 101 18 5 135 18 99
2
1 2
1 3

样例输出
50.0%
33.3%

代码

#include <cstdio>
#include <vector>
#include <set>
using namespace std;
int main() {
    int n, m, k, temp, a, b;
    scanf("%d", &n);
    vector<set<int>> v(n);
    for(int i = 0; i < n; i++) {
        scanf("%d", &m);
        set<int> s;
        for(int j = 0; j < m; j++) {
        scanf("%d", &temp);
            s.insert(temp);
        }
        v[i] = s;
    }
    scanf("%d", &k);
    for(int i = 0; i < k; i++) {
        scanf("%d %d", &a, &b);
        int nc = 0, nt = v[b-1].size();
        for(auto it = v[a-1].begin(); it != v[a-1].end(); it++) {
            if(v[b-1].find(*it) == v[b-1].end())
                nt++;
            else
                nc++;
        }
        double ans = (double)nc / nt * 100;
        printf("%.1f%%\n", ans);
    }
    return 0;
}