问题描述：

1063. Set Similarity (25)

时间限制

300 ms

内存限制

65536 kB

代码长度限制

16000 B

判题程序

Standard

作者

CHEN, Yue

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.

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 M integers 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%

只要知道stl里的set_intersection()的集合求交操作就行了。。。

需要注意的是，set_intersection()是比set_union()要快很多的，这一题如果用set_union()就运超了。。。

#include<bits/stdc++.h>
using namespace std;
int main()
{
// freopen("data.txt","r",stdin);
	int n,m,k,x,x1,x2,c,t;
	scanf("%d",&n);
	vector<set<int> > v;
	for(; n--;)
	{
		scanf("%d",&m);
		set<int> s;
		for(; m--;)
		{
			scanf("%d",&x);
			s.insert(x);
		}
		v.push_back(s);
	}
	scanf("%d",&k);
	set<int> se;
	for(; k--;)
	{
		scanf("%d %d",&x1,&x2);
		set_intersection(v[x1-1].begin(),v[x1-1].end(),v[x2-1].begin(),v[x2-1].end(),inserter(se,se.begin()));
		c=se.size();
		t=(v[x1-1].size()+v[x2-1].size()-c);
		se.clear();
		printf("%.1f%%\n",(double)c*100/t);
	}
	return 0;
}

PAT Advanced 1063. Set Similarity (25)

1063. Set Similarity (25)

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