Submission #132378

#	Time	Username	Problem	Language	Result	Execution time	Memory
132378		dragonslayerit	Teleporters (IOI08_teleporters)	C++14	100 / 100	995 ms	44644 KiB

teleporters

#include <cstdio>
#include <map>
#include <vector>
#include <algorithm>

int xs[2000005];
int ys[2000005];

bool vis[2000005];

int next[2000005];

int explore(int a){
  int len=0;
  while(!vis[a]){
    vis[a]=true;
    a=next[a];
    len++;
  }
  return len;
}

int main(){
  int N,M;
  scanf("%d %d",&N,&M);
  for(int i=0;i<N;i++){
    scanf("%d %d",&xs[i<<1],&xs[i<<1|1]);
  }
  std::copy(xs,xs+N*2,ys);
  std::sort(ys,ys+N*2);
  for(int i=0;i<N*2;i+=2){
    int a=std::lower_bound(ys,ys+N*2,xs[i])-ys;
    int b=std::lower_bound(ys,ys+N*2,xs[i^1])-ys;
    next[a]=b+1;
    next[b]=a+1;
  }
  vis[N*2]=true;
  int score=explore(0);
  std::vector<int> cycles;
  for(int i=1;i<N*2;i++){
    if(!vis[i]){
      cycles.push_back(explore(i));
    }
  }
  if(M<cycles.size()){
    std::nth_element(cycles.begin(),cycles.end()-M,cycles.end());
  }
  std::sort(cycles.begin(),cycles.end());
  while(M>0&&cycles.size()){
    score+=cycles.back()+2;
    cycles.pop_back();
    M--;
  }
  printf("%d\n",score+M/2*4+M%2);
  return 0;
}

Compilation message (stderr)

teleporters.cpp: In function 'int main()':
teleporters.cpp:45:7: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(M<cycles.size()){
      ~^~~~~~~~~~~~~~
teleporters.cpp:25:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&N,&M);
   ~~~~~^~~~~~~~~~~~~~~
teleporters.cpp:27:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d",&xs[i<<1],&xs[i<<1|1]);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
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