#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define mp make_pair
typedef pair<int, int> ii;
const int len = 1e5+3;
int n, m, cnt;
int par[len], sum[len], po[len], val[len], pre[len], star[len], ord[len];
vector<ii> adj[len], vec;
struct dsu{
int anc[len], sz[len], low[len];
void init(){
for (int i = 1; i <= n; i++)
anc[i] = i, sz[i] = 1, low[i] = i;
}
int fin(int i){
if (anc[i] == i) return i;
return anc[i] = fin(anc[i]);
}
void join(int i, int j){
i = fin(i), j = fin(j);
if (i == j) return;
if (sz[i] > sz[j])
sz[i] += sz[j], anc[j] = i;
else
sz[j] += sz[i], anc[i] = j;
low[j] = low[i];
}
};
dsu gen, loc;
void build(int u){
cnt++;
star[u] = cnt;
ord[cnt] = u;
for (int j = 0; j < adj[u].size(); j++){
ii v = adj[u][j];
if (v.fi == par[u])
continue;
par[v.fi] = u;
build(v.fi);
}
}
void fix(int u){
while (po[u] > 0){
int v = val[po[u]];
po[u] = pre[po[u]];
//printf("lca: %d - %d\n", u, v);
sum[u]++;
sum[v]++;
sum[loc.low[loc.fin(v)]] -= 2;
}
for (int j = 0; j < adj[u].size(); j++){
ii v = adj[u][j];
if (par[u] == v.fi)
continue;
fix(v.fi);
loc.join(u, v.fi);
}
}
void dfs(int u){
for (int j = 0; j < adj[u].size(); j++){
ii v = adj[u][j];
if (par[u] != v.fi){
dfs(v.fi);
sum[u] += sum[v.fi];
if (sum[v.fi])
adj[u][j].se = 0;
}
else{
if (sum[u])
adj[u][j].se = 0;
}
}
}
void print(int u){
for (int j = 0; j < adj[u].size(); j++){
ii v = adj[u][j];
if (par[u] == v.fi)
continue;
if (v.se)
printf("%d %d\n", u, v.fi);
print(v.fi);
}
}
int main(){
scanf("%d %d", &n, &m);
gen.init();
while (m > 0){
int k = min(n, m);
m -= k;
//printf("round starts with k = %d\n", k);
cnt = 0;
loc.init();
vec.clear();
for (int i = 1; i <= n; i++){
par[i] = 0;
sum[i] = 0;
po[i] = 0;
//lca[i].clear();
//vector<int>().swap(lca[i]);
}
for (int i = 1; i <= k; i++){
int a, b;
scanf("%d %d", &a, &b);
//printf("edge: a = %d, b = %d\n", a, b);
if (gen.fin(a) != gen.fin(b)){
//printf("tree edge\n");
adj[a].pb(mp(b, 1));
adj[b].pb(mp(a, 1));
gen.join(a, b);
}
else{
vec.pb(mp(a, b));
//printf("cross edge\n");
}
}
for (int i = 1; i <= n; i++)
if (!par[i])
build(i);
for (int i = 0; i < vec.size(); i++){
int a = vec[i].fi, b = vec[i].se;
if (star[a] > star[b])
swap(a, b);
val[i+1] = a;
pre[i+1] = po[b];
po[b] = i+1;
}
for (int i = 1; i <= n; i++)
if (!par[i])
fix(i);
for (int i = 1; i <= n; i++)
if (!par[i])
dfs(i);
}
for (int i = 1; i <= n; i++)
if (!par[i])
print(i);
return 0;
}
Compilation message
pipes.cpp: In function 'void build(int)':
pipes.cpp:47:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int j = 0; j < adj[u].size(); j++){
~~^~~~~~~~~~~~~~~
pipes.cpp: In function 'void fix(int)':
pipes.cpp:70:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int j = 0; j < adj[u].size(); j++){
~~^~~~~~~~~~~~~~~
pipes.cpp: In function 'void dfs(int)':
pipes.cpp:81:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int j = 0; j < adj[u].size(); j++){
~~^~~~~~~~~~~~~~~
pipes.cpp: In function 'void print(int)':
pipes.cpp:99:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int j = 0; j < adj[u].size(); j++){
~~^~~~~~~~~~~~~~~
pipes.cpp: In function 'int main()':
pipes.cpp:154:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i = 0; i < vec.size(); i++){
~~^~~~~~~~~~~~
pipes.cpp:111:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d", &n, &m);
~~~~~^~~~~~~~~~~~~~~~~
pipes.cpp:134:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d", &a, &b);
~~~~~^~~~~~~~~~~~~~~~~
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
4 ms |
2680 KB |
Output is correct |
| 2 |
Correct |
4 ms |
2808 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
11 ms |
3192 KB |
Output is correct |
| 2 |
Correct |
10 ms |
3192 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
246 ms |
3064 KB |
Output is correct |
| 2 |
Correct |
243 ms |
3064 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
484 ms |
3704 KB |
Output is correct |
| 2 |
Correct |
569 ms |
3892 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
822 ms |
5200 KB |
Output is correct |
| 2 |
Correct |
598 ms |
5752 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1280 ms |
9728 KB |
Output is correct |
| 2 |
Correct |
1079 ms |
9840 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
2124 ms |
10472 KB |
Output is correct |
| 2 |
Correct |
1893 ms |
10248 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3159 ms |
12136 KB |
Output is correct |
| 2 |
Runtime error |
3140 ms |
53412 KB |
Memory limit exceeded (if you are sure your verdict is not MLE, please contact us) |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
4014 ms |
12364 KB |
Output is correct |
| 2 |
Runtime error |
3805 ms |
65032 KB |
Memory limit exceeded (if you are sure your verdict is not MLE, please contact us) |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
5017 ms |
11720 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
