1063 Set Similarity (25 分)
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 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%
一,注意点
1,查找两个set中的相同元素不用两个平方级的for,以后最好也杜绝这种第二个for从头开始的写法,会超时的。
2,set中的常见操作时间复杂度,insert()为O(logN),find()为O(logN),erase()单个元素为O(1),erase()两个元素为O(last-first),size()为O(1),clear()为O(N).
别忘了用这些set的自带函数。
二,我的代码
#include<cstdio>
#include<set>
using namespace std;
const int max_n = 55;
set<int> set_list[max_n];
void comparing(int set_1, int set_2) {
int total_size = 0, total_num = 0, same_num = 0;
// double ans = 0;
for (set<int>::iterator it = set_list[set_1].begin(); it != set_list[set_1].end(); it++) {
if (set_list[set_2].find(*it) != set_list[set_2].end()) {
same_num++;
}
}
total_size = set_list[set_1].size() + set_list[set_2].size();
total_num = total_size - same_num;
printf("%.1f%%\n", 100.0 * same_num / total_num);
}
int main() {
int N = 0;
int num = 0;
int factor = 0;
scanf("%d", &N);
for (int i = 1; i <= N; i++) {
scanf("%d", &num);
for (int j = 0; j < num; j++) {
scanf("%d", &factor);
set_list[i].insert(factor);
}
}
int set_1 = 0, set_2 = 0;
scanf("%d", &N);
for (int i = 0; i < N; i++) {
scanf("%d %d", &set_1, &set_2);
comparing(set_1, set_2);
}
return 0;
}