Submission #229552

#	Time	Username	Problem	Language	Result	Execution time	Memory
229552		FieryPhoenix	Teleporters (IOI08_teleporters)	C++11	100 / 100	458 ms	47384 KiB

teleporters

#include <bits/stdc++.h>
using namespace std;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef long long ll;
typedef long double ld;
#define INF 2001001001
#define MOD 1000000007

int N,M;
int L[1000001],R[1000001];
int adj[2000005];
int tele[2000005];
int label[2000005];
bool vis[2000005];
int ans=0;
int cycleSize;
vector<int>cyc;

void dfs(int node, int from){
  vis[node]=true;
  if (!vis[adj[node]]){
    cycleSize++;
    if (from==0) ans++;
    dfs(adj[node],from);
  }
}

int main()
{
  //ios_base::sync_with_stdio(0);cin.tie(0);
  //freopen (".in","r",stdin);
  //freopen (".out","w",stdout);
  scanf("%d%d",&N,&M);
  for (int i=1;i<=N;i++){
    scanf("%d%d",&L[i],&R[i]);
    tele[L[i]]=i;
    tele[R[i]]=i;
  }
  int cnt=0;
  for (int i=1;i<=2000000;i++){
    if (tele[i]!=0){
      cnt++;
      label[i]=cnt;
    }
  }
  for (int i=1;i<=2000000;i++){
    if (tele[i]!=0){
      if (L[tele[i]]==i)
	adj[label[i]-1]=label[R[tele[i]]];
      else
	adj[label[i]-1]=label[L[tele[i]]];
    }
  }
  dfs(0,0);
  for (int i=1;i<=N*2;i++)
    if (!vis[i]){
      cycleSize=0;
      dfs(i,i);
      cyc.push_back(cycleSize+1);
    }
  sort(cyc.begin(),cyc.end());
  reverse(cyc.begin(),cyc.end());
  /*
  cout<<ans<<endl;
  cout<<"CYCLES: ";
  for (int x:cyc)
    cout<<x<<' ';
    cout<<endl;
  */
  for (int i=0;i<(int)cyc.size();i++){
    if (M>0){
      ans+=cyc[i]+2;
      M--;
    }
  }
  while (M>=2){
    M-=2;
    ans+=4;
  }
  if (M==1) ans++;
  cout<<ans<<endl;
  return 0;
}

Compilation message (stderr)

teleporters.cpp: In function 'int main()':
teleporters.cpp:34:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&N,&M);
   ~~~~~^~~~~~~~~~~~~~
teleporters.cpp:36:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d",&L[i],&R[i]);
     ~~~~~^~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 5 / 5
• Subtask 5: 5 / 5
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• Subtask 15: 5 / 5
• Subtask 16: 5 / 5
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• Subtask 18: 5 / 5
• Subtask 19: 5 / 5
• Subtask 20: 5 / 5