#include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define sz(a) a.size()
typedef long long ll;
typedef pair<int, int> pii;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<class T> using oset=tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
int degree[1000005];
vector<int> adj[1000005];
bool vis[1000005];
int N, L;
multiset<int> degrees;
int deg2=0;
int cmp =0;
int re = 0;
bool wrk = true;
bool canwrk[1000005];
int deg4 = 0;
void Link(int a, int b){
if(degrees.find(degree[a]) != degrees.end())degrees.erase(degrees.find(degree[a]));
if(degrees.find(degree[b]) != degrees.end())degrees.erase(degrees.find(degree[b]));
degree[a]++;
degree[b]++;
adj[a].pb(b);
adj[b].pb(a);
if(adj[a].size() == 4)deg4++;
if(adj[b].size() == 4)deg4++;
degrees.insert(degree[a]);
degrees.insert(degree[b]);
}
void dfs(int u){
vis[u] = true;
cmp++;
int deg = 0;
for(int v : adj[u]){
if(v != re)deg++;
if(!vis[v] && v != re){
dfs(v);
}
}
//cout << u << " " << deg << '\n';
if(deg > 2)wrk = false;
if(deg == 2)deg2++;
}
int CountCritical(){
/**
int cnt4 = 0;
for(int i = 0; i < N;i ++){
if(degrees[i] >= 4)cnt4++;
}
if(cnt4 > 1)return 0;
if(cnt4 == 1)return 1;
//check for degrees of 3
multiset<int> set;
for(int i = 0; i < N;i ++)set.insert(degrees[i]);
for(int i = 0; i < N;i ++){
if(degrees[i] == 3){
for(int u : adj[i]){
//check if removing this makes chains
vector<int> removes;
for(int v : adj[u]){
degrees[v]--;
}
}
}
}
int mxDeg = 0;
for(int i =0; i < N;i ++){
mxDeg = max(mxDeg, degrees[i]);
}
if(mxDeg <= 2)return N;
**/
if(deg4 == 1)return 1;
if(deg4 > 1)return 0;
int ans = 0;
for(int i = 0; i < N;i ++){
re = i;
wrk = true;
if(canwrk[i] == false)continue;
memset(vis, false, sizeof(vis));
for(int j = 0;j < N; j++){
if(!vis[j] && j != i){
deg2=0;
cmp = 0;
dfs(j);
if(cmp == 1)continue;
if(deg2 > cmp-2)wrk = false;
//cout << i << " " << j << " " << cmp << " " << deg2 << '\n';
}
if(!wrk)break;
}
if(wrk)ans++;
canwrk[i] = wrk;
}
//cout << '\n';
return ans;
}
int main(){
memset(canwrk, true, sizeof(canwrk));
cin >> N >> L;
for(int i = 0; i < L;i ++){
int x;
cin >> x;
if(x == -1){
cout << CountCritical() << '\n';
}
else{
int y;
cin >> y;
Link(x,y);
}
}
}
Compilation message
/tmp/ccmXXS3n.o: In function `main':
rings.cpp:(.text.startup+0x0): multiple definition of `main'
/tmp/ccAZOsGB.o:grader.cpp:(.text.startup+0x0): first defined here
/tmp/ccAZOsGB.o: In function `main':
grader.cpp:(.text.startup+0x84): undefined reference to `Init(int)'
collect2: error: ld returned 1 exit status
