| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 1043597 | Ausp3x | Parachute rings (IOI12_rings) | C++17 | 0 ms | 0 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.
// 人外有人，天外有天
// author: Ausp3x
#pragma GCC optimize("O1, O2, O3, Ofast, unroll-loops")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#define fi first
#define se second
#define pb push_back
#define DEBUG
typedef long long lng;
int const INF32 = 0x3f3f3f3f;
lng const INF64 = 0x3f3f3f3f3f3f3f3f;
struct UnionFind {
int n;
vector<int> link, node_size, edge_size;
void init(int n) {
this->n = n;
link.resize(n + 1);
iota(link.begin(), link.end(), 0);
node_size.resize(n + 1, 1);
edge_size.resize(n + 1);
}
int findSet(int v) {
if (v == link[v]) {
return link[v];
}
return link[v] = findSet(link[v]);
}
bool isSameSet(int a, int b) {
return findSet(a) == findSet(b);
}
void uniteSets(int a, int b) {
a = findSet(a);
b = findSet(b);
if (node_size[a] < node_size[b]) {
swap(a, b);
}
if (a == b) {
edge_size[a]++;
return;
}
node_size[a] += node_size[b];
edge_size[a] += edge_size[b] + 1;
link[b] = a;
return;
}
void debugPrint() {
cout << n << endl;
cout << "link:" << endl;
for (int x : link)
cout << x << ' ';
cout << endl;
cout << "node_size:" << endl;
for (int x : node_size)
cout << x << ' ';
cout << endl;
cout << "edge_size:" << endl;
for (int x : edge_size)
cout << x << ' ';
cout << endl;
return;
}
};
int N, E = 0;
int simple_cycle_size = -1;
vector<int> edg_cnts;
vector<vector<int>> adjl;
UnionFind uf_all;
vector<vector<int>> cands_edg_cnts(4);
vector<UnionFind> uf_cands(4);
void Init(int n) {
N = n;
edg_cnts.resize(n);
adjl.resize(n);
uf_all.init(n);
for (int i = 0; i < 4; i++)
cands_edg_cnts[i].resize(n);
for (int i = 0; i < 4; i++)
uf_cands[i].init(n);
return;
}
bool is_impossible = false;
vector<bool> is_pos_cands(4, true);
vector<int> idxs(4);
void Link(int a, int b) {
if (edg_cnts[a] < edg_cnts[b])
swap(a, b);
edg_cnts[a]++;
edg_cnts[b]++;
adjl[a].pb(b);
adjl[b].pb(a);
if (edg_cnts[a] > E && edg_cnts[a] == 3) {
E = edg_cnts[a];
uf_all.uniteSets(a, b);
assert(adjl[a].size() == 3);
idxs[0] = a;
for (int i = 0; i < 3; i++)
idxs[i + 1] = adjl[a][i];
// for (int x : idxs)
// cout << x << ' ';
// cout << endl;
for (int i = 0; i < 4; i++) {
for (int j = 0; j < N; j++) {
if (j == idxs[i])
continue;
for (int k : adjl[j]) {
if (k == idxs[i])
continue;
if (k < j)
continue;
cands_edg_cnts[i][j]++;
cands_edg_cnts[i][k]++;
if (cands_edg_cnts[i][j] >= 3 || cands_edg_cnts[i][k] >= 3)
is_pos_cands[i] = false;
if (uf_cands[i].findSet(j) == uf_cands[i].findSet(k))
is_pos_cands[i] = false;
uf_cands[i].uniteSets(j, k);
}
}
}
// for (int i = 0; i < 4; i++) {
// for (int j = 0; j < N; j++)
// cout << cands_edg_cnts[i][j] << ' ';
// cout << endl;
// }
bool has_candidates = false;
for (int i = 0; i < 4; i++)
has_candidates |= is_pos_cands[i];
if (!has_candidates)
is_impossible = true;
// cout << is_impossible << endl;
return;
}
E = max(E, edg_cnts[a]);
if (E == 2 && uf_all.findSet(a) == uf_all.findSet(b)) {
uf_all.uniteSets(a, b);
if (simple_cycle_size != -1) {
is_impossible = true;
return;
}
simple_cycle_size = uf_all.node_size[uf_all.findSet(a)];
return;
}
uf_all.uniteSets(a, b);
if (E >= 3) {
for (int i = 0; i < 4; i++) {
if (idxs[i] == a || idxs[i] == b)
continue;
cands_edg_cnts[i][a]++;
cands_edg_cnts[i][b]++;
if (cands_edg_cnts[i][a] >= 3 || cands_edg_cnts[i][b] >= 3)
is_pos_cands[i] = false;
if (uf_cands[i].findSet(a) == uf_cands[i].findSet(b))
is_pos_cands[i] = false;
uf_cands[i].uniteSets(a, b);
}
bool has_candidates = false;
for (int i = 0; i < 4; i++)
has_candidates |= is_pos_cands[i];
if (!has_candidates)
is_impossible = true;
return;
}
return;
}
int CountCritical() {
if (is_impossible)
return 0;
if (E <= 1)
return N;
if (E == 2)
return (simple_cycle_size == -1 ? N : simple_cycle_size);
return accumulate(is_pos_cands.begin(), is_pos_cands.end(), 0);
}
#ifdef DEBUG
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int t = 1;
cin >> t;
while (t--) {
int n, l;
cin >> n >> l;
Init(n);
while (l--) {
int a;
cin >> a;
if (a == -1) {
cout << CountCritical() << endl;
continue;
}
int b;
cin >> b;
Link(a, b);
}
}
return 0;
}
#endif