Submission #1011866

#	Time	Username	Problem	Language	Result	Execution time	Memory
1011866		PenguinsAreCute	Pipes (CEOI15_pipes)	C++17	20 / 100	1086 ms	65536 KiB

pipes

#include <vector>
#include <cstdio>
#include <bitset>
using namespace std;
typedef vector<int> vi;
#define pb push_back
#define REP(i, a, b) for(int i = a; i < b; i++)
#define MAXN 100005
vi adj[MAXN], adj_dfs3[MAXN];
int h[MAXN], crossEdges[MAXN], par[MAXN];
bitset<MAXN> visited;
void dfs(int x) {
	visited[x] = true;
	for(auto i: adj[x]) if(!visited[i]) {
		par[i]=x;
		adj_dfs3[x].pb(i);
		h[i]=h[x]+1;
		dfs(i);
	}
}
int dp(int x) {
	if(visited[x]) return crossEdges[x];
	visited[x] = 1;
	//crossEdges[x]=bEdgeU[x]-bEdgeD[x];
	for(auto i:adj_dfs3[x]) if(h[i]>h[x]) crossEdges[x]+=dp(i);
	return crossEdges[x];
}
int main() {
	int N, E, A, B, ans; scanf("%d %d",&N,&E);
	REP(i,0,E) {
		scanf("%d %d",&A,&B);
		adj[A].pb(B);
		adj[B].pb(A);
	}
	REP(i,1,N+1)if(!visited[i]) dfs(i);
	REP(i,1,N+1) visited[i]=0;
	REP(i,1,N+1) for(auto j: adj[i]) {
		if(h[i]>h[j]) crossEdges[i]++;
		else crossEdges[i]--;
	}
	REP(i,1,N+1) if(par[i]&&dp(i)==1) printf("%d %d\n",i,par[i]);
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:29:18: warning: unused variable 'ans' [-Wunused-variable]
   29 |  int N, E, A, B, ans; scanf("%d %d",&N,&E);
      |                  ^~~
pipes.cpp:29:28: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |  int N, E, A, B, ans; scanf("%d %d",&N,&E);
      |                       ~~~~~^~~~~~~~~~~~~~~
pipes.cpp:31:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |   scanf("%d %d",&A,&B);
      |   ~~~~~^~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10