【PAT甲级】1063 Set Similarity (25)

题目链接

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 (<=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.

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%

题意：求两个集合的交集与并集，计算相似度

思路：set_union,set_intersection

代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <cmath>
#include <vector>
#include <sstream>
#include <algorithm>
using namespace std;
#define rep(i,a,n) for(int i=a;i<n;i++)
#define mem(a,n) memset(a,n,sizeof(a))
#define lowbit(i) ((i)&(-i))
typedef long long ll;
typedef unsigned long long ull;
const ll INF=0x3f3f3f3f;
const int N = 1e6+5;

set<int>st[55];
int main() {
    int n,q,x,m,a,b;
    scanf("%d",&n);
    rep(i,0,n) {
        scanf("%d",&m);
        while(m--) {
            scanf("%d",&x);
            st[i].insert(x);
        }
    }
    scanf("%d",&q);
    while(q--) {
        scanf("%d%d",&a,&b);
        a--,b--;
        vector<int>tot, same;
        /**back_inserter(container)：使用push_back()在容器尾端安插元素，元素排列顺序和安插顺序相同。
        只有在提供了push_back()成员函数的容器才能使back_inserter(container)这样的容器有：vector,deque,list

        set_union,set_intersection 集合的并集和交集运算
       */
        set_union(st[a].begin(),st[a].end(),st[b].begin(),st[b].end(),back_inserter(tot));
        set_intersection(st[a].begin(),st[a].end(),st[b].begin(),st[b].end(),back_inserter(same));
        printf("%.1f%%\n",100.0*same.size()/tot.size());
    }
    return 0;
}

参考博客：

https://blog.csdn.net/tianxiaolu1175/article/details/48413163/

https://blog.csdn.net/cillyb/article/details/60993193

https://blog.csdn.net/xianyun2009/article/details/50354581

【PAT甲级】1063 Set Similarity (25)

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