#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define int ll
#define FOR(i, a, b) for (int i=(a); i<(b); i++)
#define REP(i, n) FOR(i, 0, n)
#define REP1(i, n) FOR(i, 1, n+1)
#define RREP(i, n) for (int i=(n)-1; i>=0; i--)
#define pii pair<int, int>
#define f first
#define s second
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) (int)((x).size())
const ll maxn = 2e5+5;
int n, m;
vector<int> graph[maxn];
vector<int> in(maxn);
vector<bool> occ(maxn);
void inp(){
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
cin>>n>>m;
REP(i, m){
int u, v; cin>>u>>v;
graph[u].pb(v);
in[v]++;
}
}
vector<pii> res;
void solve(){
queue<int> qu;
REP1(i, n){
if (in[i] == 0) qu.push(i);
}
vector<int> topo;
while(qu.size()){
int x=qu.front(); qu.pop();
occ[x]=1;
topo.pb(x);
REP(i, SZ(graph[x])){
in[graph[x][i]]--;
if (in[graph[x][i]] == 0){
qu.push(graph[x][i]);
}
}
}
bool gg=0;
REP1(i, n){
if (occ[i] == 0){
gg=1;
break;
}
}
if (gg) {
if (m==n-1) assert(0);
cout<<-1<<endl;
return;
}
assert(SZ(topo)==n);
cout<<n<<endl;
REP(i, n){
cout<<topo[i]<<' '<<0<<endl;
}
}
signed main(){
inp();
solve();
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
6612 KB |
Output is correct |
2 |
Correct |
3 ms |
6612 KB |
Output is correct |
3 |
Correct |
3 ms |
6596 KB |
Output is correct |
4 |
Correct |
3 ms |
6612 KB |
Output is correct |
5 |
Correct |
3 ms |
6612 KB |
Output is correct |
6 |
Correct |
3 ms |
6612 KB |
Output is correct |
7 |
Correct |
3 ms |
6612 KB |
Output is correct |
8 |
Correct |
3 ms |
6612 KB |
Output is correct |
9 |
Correct |
4 ms |
6612 KB |
Output is correct |
10 |
Correct |
3 ms |
6620 KB |
Output is correct |
11 |
Correct |
4 ms |
6612 KB |
Output is correct |
12 |
Correct |
3 ms |
6612 KB |
Output is correct |
13 |
Correct |
3 ms |
6612 KB |
Output is correct |
14 |
Correct |
3 ms |
6612 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
338 ms |
15008 KB |
Output is correct |
2 |
Correct |
333 ms |
14908 KB |
Output is correct |
3 |
Correct |
163 ms |
10952 KB |
Output is correct |
4 |
Correct |
328 ms |
14980 KB |
Output is correct |
5 |
Correct |
326 ms |
15004 KB |
Output is correct |
6 |
Correct |
420 ms |
14896 KB |
Output is correct |
7 |
Correct |
334 ms |
14964 KB |
Output is correct |
8 |
Correct |
258 ms |
13152 KB |
Output is correct |
9 |
Correct |
329 ms |
15032 KB |
Output is correct |
10 |
Correct |
329 ms |
14912 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
6612 KB |
Output is correct |
2 |
Correct |
3 ms |
6612 KB |
Output is correct |
3 |
Correct |
3 ms |
6596 KB |
Output is correct |
4 |
Correct |
3 ms |
6612 KB |
Output is correct |
5 |
Correct |
3 ms |
6612 KB |
Output is correct |
6 |
Correct |
3 ms |
6612 KB |
Output is correct |
7 |
Correct |
3 ms |
6612 KB |
Output is correct |
8 |
Correct |
3 ms |
6612 KB |
Output is correct |
9 |
Correct |
4 ms |
6612 KB |
Output is correct |
10 |
Correct |
3 ms |
6620 KB |
Output is correct |
11 |
Correct |
4 ms |
6612 KB |
Output is correct |
12 |
Correct |
3 ms |
6612 KB |
Output is correct |
13 |
Correct |
3 ms |
6612 KB |
Output is correct |
14 |
Correct |
3 ms |
6612 KB |
Output is correct |
15 |
Correct |
338 ms |
15008 KB |
Output is correct |
16 |
Correct |
333 ms |
14908 KB |
Output is correct |
17 |
Correct |
163 ms |
10952 KB |
Output is correct |
18 |
Correct |
328 ms |
14980 KB |
Output is correct |
19 |
Correct |
326 ms |
15004 KB |
Output is correct |
20 |
Correct |
420 ms |
14896 KB |
Output is correct |
21 |
Correct |
334 ms |
14964 KB |
Output is correct |
22 |
Correct |
258 ms |
13152 KB |
Output is correct |
23 |
Correct |
329 ms |
15032 KB |
Output is correct |
24 |
Correct |
329 ms |
14912 KB |
Output is correct |
25 |
Correct |
153 ms |
14288 KB |
Output is correct |
26 |
Correct |
124 ms |
14704 KB |
Output is correct |
27 |
Correct |
139 ms |
15060 KB |
Output is correct |
28 |
Correct |
201 ms |
16320 KB |
Output is correct |
29 |
Correct |
113 ms |
15184 KB |
Output is correct |
30 |
Correct |
177 ms |
16032 KB |
Output is correct |
31 |
Correct |
22 ms |
8652 KB |
Output is correct |
32 |
Correct |
356 ms |
15064 KB |
Output is correct |
33 |
Correct |
448 ms |
18220 KB |
Output is correct |
34 |
Correct |
362 ms |
15376 KB |
Output is correct |
35 |
Correct |
466 ms |
18140 KB |
Output is correct |
36 |
Correct |
353 ms |
14628 KB |
Output is correct |
37 |
Correct |
442 ms |
17340 KB |
Output is correct |
38 |
Correct |
400 ms |
16304 KB |
Output is correct |
39 |
Correct |
443 ms |
18008 KB |
Output is correct |
40 |
Correct |
419 ms |
17056 KB |
Output is correct |
41 |
Correct |
433 ms |
16812 KB |
Output is correct |
42 |
Correct |
478 ms |
18448 KB |
Output is correct |
43 |
Correct |
384 ms |
15528 KB |
Output is correct |
44 |
Correct |
460 ms |
18520 KB |
Output is correct |
45 |
Correct |
360 ms |
15004 KB |
Output is correct |
46 |
Correct |
416 ms |
16908 KB |
Output is correct |