Submission #243847

#	Time	Username	Problem	Language	Result	Execution time	Memory
243847		errorgorn	Pipes (CEOI15_pipes)	C++14	10 / 100	2589 ms	65540 KiB

pipes

//雪花飄飄北風嘯嘯
//天地一片蒼茫

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << " is " << x << endl;

#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()

ll MAX(ll a){return a;}
ll MIN(ll a){return a;}
template<typename... Args>
ll MAX(ll a,Args... args){return max(a,MAX(args...));}
template<typename... Args>
ll MIN(ll a,Args... args){return min(a,MIN(args...));}

#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>

mt19937 rng(chrono::system_clock::now().time_since_epoch().count());

int n,m;
vector<int> al[100005];
int dfs_time[100005]; ///first time to reach vertex
int low[100005]; ///lowest time vertex it can reach with 1 backtrack
int dfs_counter=1;
void dfs(int i,int j){ ///j is parent of i
    dfs_time[i]=low[i]=dfs_counter++;
    for (vector<int>::iterator it=al[i].begin();it!=al[i].end();it++){
        if (!dfs_time[*it]){ ///uninitialized vertex
            dfs(*it,i);
            low[i]=min(low[i],low[*it]);
			
			if (low[*it]>dfs_time[i]){
				cout<<*it<<" "<<i<<endl;
			}
        }
        else if (*it!=j){ ///make sure it is a back edge
            low[i]=min(low[i],dfs_time[*it]);
        }
    }
}


int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	
	cin>>n>>m;
	
	int a,b;
	rep(x,0,m){
		cin>>a>>b;
		
		al[a].push_back(b);
		al[b].push_back(a);
	}
	
	rep(x,1,n+1) if (!dfs_time[x]) dfs(x,-1);
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 10 / 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