#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
int cmp[100001];
ll sz[100001], ans = 0;
set<int> child[100001], graph[100001], rgraph[100001];
queue<pair<int, int>> to_merge;
void insert_weak_connection(int A, int B) {
graph[A].insert(B);
rgraph[B].insert(A);
// If there's A new strong connection between A's and B's components, merge them
if (graph[B].count(A)) to_merge.push({A, B});
}
int dsu_size(int A) { return child[A].size() + graph[A].size() + rgraph[A].size(); }
int find(int A) { return (A == cmp[A] ? A : cmp[A] = find(cmp[A])); }
void onion(int A, int B) {
if (A == B) return;
// Merge the smaller component into the larger
if (dsu_size(A) < dsu_size(B)) swap(A, B);
// Add new contribution
ans += sz[B] * child[A].size() + sz[A] * child[B].size();
// DSU stuff
cmp[B] = A;
sz[A] += sz[B];
// Merge children of B into A
for (int i : child[B]) {
if (child[A].count(i)) ans -= sz[A];
else child[A].insert(i);
}
// Erase the connections
graph[A].erase(B), rgraph[A].erase(B);
graph[B].erase(A), rgraph[B].erase(A);
// Merge the weak connections to other components
for (int i : graph[B]) {
rgraph[i].erase(B);
insert_weak_connection(A, i);
}
for (int i : rgraph[B]) {
graph[i].erase(B);
insert_weak_connection(i, A);
}
}
int main() {
cin.tie(0)->sync_with_stdio(0);
int n, m;
cin >> n >> m;
for (int i = 1; i <= n; i++) {
cmp[i] = i;
sz[i] = 1;
child[i].insert(i);
}
while (m--) {
int A, B;
cin >> A >> B;
B = find(B);
A = find(A);
// If A isn't in B's component and doesn't already follow someone in B's component...
if (find(A) != B && !child[B].count(A)) {
// We insert A as A follower of B and add sz[find(B)] to the answer
child[B].insert(A);
ans += sz[B];
// Add connections between components
insert_weak_connection(A, B);
// We may have to merge multiple components for each new event
while (to_merge.size()) {
tie(A, B) = to_merge.front();
to_merge.pop();
onion(find(A), find(B));
}
}
cout << ans << '\n';
}
return 0;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 2 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 3 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 4 |
Correct |
11 ms |
14444 KB |
Output is correct |
| 5 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 6 |
Incorrect |
10 ms |
14444 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 2 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 3 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 4 |
Correct |
11 ms |
14444 KB |
Output is correct |
| 5 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 6 |
Incorrect |
10 ms |
14444 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 2 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 3 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 4 |
Correct |
11 ms |
14444 KB |
Output is correct |
| 5 |
Correct |
10 ms |
14444 KB |
Output is correct |
| 6 |
Incorrect |
10 ms |
14444 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
