Submission #1116157

#	Time	Username	Problem	Language	Result	Execution time	Memory
1116157		vjudge1	Pipes (CEOI15_pipes)	C++17	100 / 100	1947 ms	13920 KiB

pipes

#include<bits/stdc++.h>
using namespace std;
#define pb push_back
 
const int lim=1e5+1;
 
int parent[lim];
int find(int i){
  if(i==parent[i])return i;
  return parent[i]=find(parent[i]);
}
void unite(int i,int j){
  i=find(i),j=find(j);
  parent[i]=j;
}
 
struct vec{
  int*targ=new int[2],size=2,have=0;
  void pb(int t){
    if(have==size){
      int*newy=new int[int(size*1.5)];
      for(int i=0;i<size;i++)newy[i]=targ[i];
      size*=1.5;
      delete targ;
      targ=newy;
    }
    targ[have++]=t;
  }
  void clear(){
    have=0;
    size=2;
    delete targ;
    targ=new int[2];
  }
};
 
vec v[lim];
vector<pair<int,int>>edges;
 
int tin[lim],tout[lim],tt=1;
 
int dfs(int node,int par){
  if(tin[node])return tin[node];
  tout[node]=tin[node]=tt++;
  for(int i=0;i<v[node].have;i++){
    int j=v[node].targ[i];
    if(j==par)continue;
    if(tin[j]){
      tout[node]=min(tout[node],tin[j]);
      unite(node,j);
    }else{
      int res=dfs(j,node);
      if(res<=tin[node]){
        unite(node,j);
      }
      tout[node]=min(tout[node],res);
    }
  }
  return tout[node];
}
 
int n,m;
void findans(){
  for(int i=0;i<=n;i++)v[i].clear();
  for(auto[x,y]:edges){
    v[find(x)].pb(find(y));
    v[find(y)].pb(find(x));
  }
  for(int i=0;i<=n;i++){
    tout[i]=tin[i]=0;
  }
  tt=1;
  for(int i=1;i<=n;i++){
    if(!tin[i])dfs(i,0);
  }
  for(int i=0;i<edges.size();i++){
    if(find(edges[i].first)==find(edges[i].second)){
      swap(edges[i],edges.back());
      edges.pop_back();
      i--;
    }
  }
}
 
int main(){
  cin>>n>>m;
  for(int i=1;i<=n;i++)parent[i]=i;
  for(int i=0;i<m;i++){
    int x,y;
    cin>>x>>y;
    if(find(x)!=find(y))edges.pb({x,y});
    if(edges.size()==150000)findans();
  }
  findans();
  for(auto[x,y]:edges)cout<<x<<' '<<y<<'\n';
}

Compilation message (stderr)

pipes.cpp: In function 'void findans()':
pipes.cpp:76:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   76 |   for(int i=0;i<edges.size();i++){
      |               ~^~~~~~~~~~~~~

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