# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
212792 | BThero | Making Friends on Joitter is Fun (JOI20_joitter2) | C++17 | 5081 ms | 27384 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#define DBG 1
// chrono::system_clock::now().time_since_epoch().count()
#include<bits/stdc++.h>
//#include<ext/pb_ds/tree_policy.hpp>
//#include<ext/pb_ds/assoc_container.hpp>
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define debug(x) if (DBG) cerr << #x << " = " << x << endl;
using namespace std;
//using namespace __gnu_pbds;
typedef long long ll;
typedef pair<int, int> pii;
//template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int MAXN = (int)1e5 + 5;
set<int> in[MAXN], out[MAXN], inv[MAXN];
vector<int> ver[MAXN];
int par[MAXN];
pii Q[MAXN];
int n, m, t;
int getPar(int x) {
if (x == par[x]) {
return x;
}
return par[x] = getPar(par[x]);
}
void uni(int a, int b) {
a = getPar(a);
b = getPar(b);
if (a == b) {
return;
}
for (int x : inv[b]) {
if (getPar(x) != a) {
inv[a].insert(x);
}
}
inv[b].clear();
for (int x : ver[b]) {
inv[a].erase(x);
ver[a].pb(x);
}
in[a].erase(b);
out[a].erase(b);
in[b].erase(a);
out[b].erase(a);
for (int x : out[b]) {
in[x].erase(b);
in[x].insert(a);
out[a].insert(x);
if (in[a].find(x) != in[a].end()) {
Q[t++] = mp(a, x);
}
}
out[b].clear();
for (int x : in[b]) {
out[x].erase(b);
out[x].insert(a);
in[a].insert(x);
if (out[a].find(x) != out[a].end()) {
Q[t++] = mp(a, x);
}
}
in[b].clear();
par[b] = a;
}
void push() {
for (int i = 0; i < t; ++i) {
uni(Q[i].fi, Q[i].se);
}
}
void solve() {
scanf("%d %d", &n, &m);
for (int i = 1; i <= n; ++i) {
par[i] = i;
ver[i].pb(i);
}
for (int i = 1; i <= m; ++i) {
int u, v;
scanf("%d %d", &u, &v);
v = getPar(v);
if (getPar(u) != v) {
inv[v].insert(u);
u = getPar(u);
out[u].insert(v);
in[v].insert(u);
if (in[u].find(v) != in[u].end()) {
t = 0;
Q[t++] = mp(u, v);
push();
}
}
ll ans = 0;
for (int j = 1; j <= n; ++j) {
if (par[j] == j) {
ans += ver[j].size() * inv[j].size();
ans += ver[j].size() * (ver[j].size() - 1);
}
}
printf("%lld\n", ans);
}
}
int main() {
int tt = 1;
while (tt--) {
solve();
}
return 0;
}
Compilation message (stderr)
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