PKU 2419 Forest

使用了bitset解决

/* 2419 Forests */#include <iostream>#include <cstring>#include <cstdio>#include <cstdlib>#include <bitset>using namespace std;const int MAX = 105;int main(){bitset<MAX> person[MAX];int per, tree;int a, b;cin >> per >> tree;while (cin >> a >> b){person[a].set(b);}bitset<MAX> visited;int count = 0;for (int i = 1; i <= per; ++ i){if (visited.test(i))continue;++ count;visited.set(i);for (int j = i + 1; j <= per; ++ j){if (person[i] == person[j])visited.set(j);}}cout << count << endl;return 0;}