| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 799302 | jlallas384 | 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.
#include <bits/stdc++.h>
using namespace std;
struct ufds{
vector<int> sz, par;
ufds(){}
ufds(int n): sz(n, 1), par(n){
iota(par.begin(), par.end(), 0);
}
int find(int a){
return par[a] == a ? a : par[a] = find(par[a]);
}
int unite(int a, int b){
a = find(a), b = find(b);
if(a == b) return 0;
if(sz[a] < sz[b]) swap(a, b);
par[b] = a;
sz[a] += sz[b];
return 1;
}
};
set<int> ans;
vector<vector<int>> g, tree;
vector<int> deg;
int n;
ufds ds;
int bad = 0;
int d4 = 0;
void Init(int N){
n = N;
g.resize(n);
tree.resize(n);
deg.resize(n);
for(int i = 0; i < n; i++){
ans.insert(i);
}
ds = ufds(n);
}
void proc(int a, int add = 1){
if(deg[a] == 4){
if(add){
d4++;
if(d4 == 2) bad = 1;
}
if(!ans.count(a)) ans = {};
else ans = {a};
}else if(deg[a] == 3){
set<int> nans;
if(ans.count(a)) nans.insert(a);
for(int u: g[a]){
if(ans.count(u)) nans.insert(u);
}
ans = nans;
}
}
int CountCritical(){
for(int i = 0; i < n; i++){
proc(i, 0);
}
if(bad) return 0;
else return ans.size();
}
int cyc = 0;
vector<int> path;
int dfs(int v, int p, int x){
path.push_back(v);
if(v == x) return 1;
for(int u: tree[v]) if(u != p){
if(dfs(u, v, x)) return 1;
}
path.pop_back();
return 0;
}
void dfs2(int v, set<int> &vis){
if(ans.count(v)) return;
vis.insert(v);
for(int u: g[v]) if(!vis.count(u)){
dfs2(u, vis);
}
}
int dfs3(int v, set<int> &v1, set<int> &v2){
if(ans.count(v)) return 0;
if(v1.count(v)) return 1;
v2.insert(v);
for(int u: g[v]) if(!v2.count(u)){
if(dfs3(u, v1, v2)) return 1;
}
return 0;
}
int dfs4(int v, int p, vector<int> &vis){
vis[v] = 2;
for(int u: g[v]){
if(!vis[u] && dfs(u, v, vis)) return 1;
else if(vis[u] == 2 && u != p) return 1;
}
return 0;
}
void Link(int a, int b){
if(bad) return;
int res = ds.unite(a, b);
deg[a]++, deg[b]++;
g[a].push_back(b);
g[b].push_back(a);
proc(a), proc(b);
if(!res){
if(!cyc){
dfs(a, -1, b);
ans = {};
for(int x: path){
ans.insert(x);
}
for(int i = 0; i < n; i++){
proc(i, 0);
}
cyc = 1;
}else{
if(ans.size() >= 3) bad = 1;
g[a].pop_back();
g[b].pop_back();
set<int> v1, v2;
dfs2(a, v1);
if(dfs3(b, v1, v2)){
bad = 1;
}
g[a].push_back(b);
g[b].push_back(a);
if(!bad){
for(int x: ans){
vector<int> vis(n);
vis[x] = 1;
for(int i = 0; i < n; i++) if(!vis[i]){
assert(!dfs(i, -1, vis));
}
}
}
}
}else{
tree[a].push_back(b);
tree[b].push_back(a);
}
}