oj.uz

Submission #527372

# Submission time Handle Problem Language Result Execution time Memory
527372 2022-02-17T09:57:34 Z jamielim Pipes (CEOI15_pipes) C++14
20 / 100
 1384 ms 14432 KB 
#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb emplace_back
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
typedef long long ll;
typedef pair<int,int> ii;
typedef pair<ii,ii> i4;
const int MOD=1000000007;
const int INF=1012345678;
const ll LLINF=1012345678012345678LL;
const double PI=3.1415926536;
const double EPS=1e-14;

const int MAXN=100005;
int n,m;
int par[MAXN],par2[MAXN]; // par, depth
int root(int x){return par[x]=(par[x]==x?x:root(par[x]));}
int root2(int x){return par2[x]=(par2[x]==x?x:root2(par2[x]));}
vector<int> adj[MAXN]; // only stores at most 2*tree

bool vis[MAXN];
int low[MAXN];
int ctr=0;
void dfs(int x){
	vis[x]=1;
	par2[x]=ctr;
	low[x]=ctr++;
	for(int i:adj[x]){
		if(i==par[x])continue;
		if(!vis[i]){
			par[i]=x;
			dfs(i);
			low[x]=min(low[x],low[i]);
			if(low[i]>par2[x])printf("%d %d\n",i+1,x+1);
		}else low[x]=min(low[x],par2[i]);
	}
}

int main(){
	scanf("%d%d",&n,&m);
	for(int i=0;i<n;i++)par[i]=par2[i]=i;
	int a,b;
	for(int i=0;i<m;i++){
		scanf("%d%d",&a,&b);a--;b--;
		//if a,b are in different trees, merge the two trees
		int ra=root(a),rb=root(b);
		if(ra!=rb){
			par[ra]=rb;
			adj[a].pb(b);
			adj[b].pb(a);
			continue;
		}
		//otherwise, take note that later we have to get rid of the entire cycle
		int r2a=root2(a),r2b=root2(b);
		if(r2a!=r2b){
			par2[r2a]=par2[r2b];
			adj[a].pb(b);
			adj[b].pb(a);
		}
	}
	memset(par,-1,sizeof(par));
	memset(par2,-1,sizeof(par2));
	memset(low,-1,sizeof(low));
	for(int i=0;i<n;i++)if(!vis[i])dfs(i);
}

Compilation message

pipes.cpp: In function 'int main()':
pipes.cpp:45:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |  scanf("%d%d",&n,&m);
      |  ~~~~~^~~~~~~~~~~~~~
pipes.cpp:49:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |   scanf("%d%d",&a,&b);a--;b--;
      |   ~~~~~^~~~~~~~~~~~~~

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 3800 KB Output is correct
2 Incorrect 2 ms 3788 KB Wrong number of edges
3 Halted 0 ms 0 KB -

Subtask #2
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 7 ms 4332 KB Output is correct
2 Incorrect 6 ms 4096 KB Wrong number of edges
3 Halted 0 ms 0 KB -

Subtask #3
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 120 ms 4844 KB Output is correct
2 Incorrect 110 ms 4792 KB Wrong number of edges
3 Halted 0 ms 0 KB -

Subtask #4
0 / 10.0

# Verdict Execution time Memory Grader output
1 Incorrect 216 ms 5920 KB Wrong number of edges
2 Halted 0 ms 0 KB -

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 343 ms 7424 KB Output is correct
2 Correct 291 ms 6944 KB Output is correct

Subtask #6
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 452 ms 11332 KB Output is correct
2 Incorrect 409 ms 7448 KB Wrong number of edges
3 Halted 0 ms 0 KB -

Subtask #7
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 734 ms 12260 KB Output is correct
2 Incorrect 632 ms 9412 KB Wrong number of edges
3 Halted 0 ms 0 KB -

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 925 ms 14068 KB Output is correct
2 Incorrect 844 ms 9284 KB Wrong number of edges
3 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1110 ms 14432 KB Output is correct
2 Incorrect 1126 ms 9364 KB Wrong number of edges
3 Halted 0 ms 0 KB -

Subtask #10
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1384 ms 13664 KB Output is correct
2 Correct 1315 ms 11004 KB Output is correct