#include <bits/stdc++.h>
#define Alora "cownav"
#define fi(i,a,b) for(int i = a; i <= b; i++)
#define fid(i,a,b) for(int i = a; i >= b; i--)
#define ll long long
#define f first
#define se second
#define pii pair<int, int>
#define getbit(i, j) ((i >> j) & 1)
#define all(v) v.begin(), v.end()
#define pb push_back
#define maxn 300005
const int M = 1e9 + 7;
using namespace std;
int n, m, sl, cnt[maxn][4];
pii ans[maxn];
queue <int> q;
vector <int> g[maxn];
int main(){
ios_base::sync_with_stdio(0);
cin.tie(NULL);
if(fopen(Alora".inp", "r")){
freopen(Alora".inp", "r", stdin);
freopen(Alora".out", "w", stdout);}
cin >> n >> m;
fi(i, 1, m){
int u, v; cin >> u >> v;
g[u].pb(v); cnt[u][1]++;
g[v].pb(u); cnt[v][0]++;
}
fi(u, 1, n) if(cnt[u][1] == 0 || cnt[u][0] == 0) q.push(u);
while(q.size()){
int u = q.front(); q.pop();
if(cnt[u][1] + cnt[u][0] == 0) continue;
int t = (cnt[u][0] > 0 ? 0 : 1);
cnt[u][t] = 0;
//cout << u << " " << t << endl;
ans[++sl] = {u, t};
for(auto v: g[u]) if(cnt[v][1 - t]){
cnt[v][1 - t]--;
if(cnt[v][1 - t] == 0) q.push(v);
}
}
fi(i, 1, n) if(cnt[i][0] + cnt[i][1]) {cout << -1; return 0;}
cout << sl << '\n';
fid(i, sl, 1) cout << ans[i].f << " " << ans[i].se << '\n';
return 0;
}
Compilation message
naboj.cpp: In function 'int main()':
naboj.cpp:24:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
24 | freopen(Alora".inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
naboj.cpp:25:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
25 | freopen(Alora".out", "w", stdout);}
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
10844 KB |
Output is correct |
2 |
Correct |
2 ms |
10844 KB |
Output is correct |
3 |
Correct |
2 ms |
10844 KB |
Output is correct |
4 |
Correct |
2 ms |
10888 KB |
Output is correct |
5 |
Correct |
2 ms |
10844 KB |
Output is correct |
6 |
Correct |
2 ms |
10844 KB |
Output is correct |
7 |
Correct |
2 ms |
10844 KB |
Output is correct |
8 |
Correct |
3 ms |
10844 KB |
Output is correct |
9 |
Correct |
2 ms |
10844 KB |
Output is correct |
10 |
Correct |
2 ms |
10844 KB |
Output is correct |
11 |
Correct |
2 ms |
10844 KB |
Output is correct |
12 |
Correct |
2 ms |
11096 KB |
Output is correct |
13 |
Correct |
2 ms |
10844 KB |
Output is correct |
14 |
Correct |
2 ms |
10864 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
98 ms |
21332 KB |
Output is correct |
2 |
Correct |
141 ms |
21288 KB |
Output is correct |
3 |
Correct |
42 ms |
17180 KB |
Output is correct |
4 |
Correct |
92 ms |
21332 KB |
Output is correct |
5 |
Correct |
112 ms |
21240 KB |
Output is correct |
6 |
Correct |
88 ms |
21328 KB |
Output is correct |
7 |
Correct |
93 ms |
21332 KB |
Output is correct |
8 |
Correct |
78 ms |
19364 KB |
Output is correct |
9 |
Correct |
87 ms |
21388 KB |
Output is correct |
10 |
Correct |
99 ms |
21332 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
10844 KB |
Output is correct |
2 |
Correct |
2 ms |
10844 KB |
Output is correct |
3 |
Correct |
2 ms |
10844 KB |
Output is correct |
4 |
Correct |
2 ms |
10888 KB |
Output is correct |
5 |
Correct |
2 ms |
10844 KB |
Output is correct |
6 |
Correct |
2 ms |
10844 KB |
Output is correct |
7 |
Correct |
2 ms |
10844 KB |
Output is correct |
8 |
Correct |
3 ms |
10844 KB |
Output is correct |
9 |
Correct |
2 ms |
10844 KB |
Output is correct |
10 |
Correct |
2 ms |
10844 KB |
Output is correct |
11 |
Correct |
2 ms |
10844 KB |
Output is correct |
12 |
Correct |
2 ms |
11096 KB |
Output is correct |
13 |
Correct |
2 ms |
10844 KB |
Output is correct |
14 |
Correct |
2 ms |
10864 KB |
Output is correct |
15 |
Correct |
98 ms |
21332 KB |
Output is correct |
16 |
Correct |
141 ms |
21288 KB |
Output is correct |
17 |
Correct |
42 ms |
17180 KB |
Output is correct |
18 |
Correct |
92 ms |
21332 KB |
Output is correct |
19 |
Correct |
112 ms |
21240 KB |
Output is correct |
20 |
Correct |
88 ms |
21328 KB |
Output is correct |
21 |
Correct |
93 ms |
21332 KB |
Output is correct |
22 |
Correct |
78 ms |
19364 KB |
Output is correct |
23 |
Correct |
87 ms |
21388 KB |
Output is correct |
24 |
Correct |
99 ms |
21332 KB |
Output is correct |
25 |
Correct |
113 ms |
20216 KB |
Output is correct |
26 |
Correct |
133 ms |
20244 KB |
Output is correct |
27 |
Correct |
117 ms |
20908 KB |
Output is correct |
28 |
Correct |
212 ms |
22544 KB |
Output is correct |
29 |
Correct |
91 ms |
19996 KB |
Output is correct |
30 |
Correct |
159 ms |
28156 KB |
Output is correct |
31 |
Correct |
22 ms |
13148 KB |
Output is correct |
32 |
Correct |
128 ms |
24384 KB |
Output is correct |
33 |
Correct |
199 ms |
29744 KB |
Output is correct |
34 |
Correct |
115 ms |
24656 KB |
Output is correct |
35 |
Correct |
253 ms |
29540 KB |
Output is correct |
36 |
Correct |
170 ms |
24120 KB |
Output is correct |
37 |
Correct |
263 ms |
28240 KB |
Output is correct |
38 |
Correct |
191 ms |
26436 KB |
Output is correct |
39 |
Correct |
261 ms |
29268 KB |
Output is correct |
40 |
Correct |
178 ms |
27476 KB |
Output is correct |
41 |
Correct |
158 ms |
27488 KB |
Output is correct |
42 |
Correct |
261 ms |
30164 KB |
Output is correct |
43 |
Correct |
133 ms |
24916 KB |
Output is correct |
44 |
Correct |
235 ms |
30292 KB |
Output is correct |
45 |
Correct |
124 ms |
24660 KB |
Output is correct |
46 |
Correct |
179 ms |
27920 KB |
Output is correct |