Submission #1056987

#	Time	Username	Problem	Language	Result	Execution time	Memory
1056987		Malix	Thousands Islands (IOI22_islands)	C++17	17.35 / 100	16 ms	5376 KiB

islands

#include "islands.h"

#include <variant>
using namespace std;
 
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
typedef tuple<int,int,int> tii;
typedef vector<ll> li;
typedef vector<li> lii;
 
#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define LSOne(s) ((s)&(-s))
 
ll INF=1e18+10;
int inf=1e9+10;
ll M=1e9+7;

int n,m; 
vi ans;
vector<pii> arr;
vi vis;

void bfs(int x){
  vis[x]=1;
  int s=arr[x].size();
  if(s==1){
    ans.PB(-1);
    return;
  }
  if(s==2){
    int k=0;
    if(vis[arr[x][0].F])k++;
    ans.PB(arr[x][k].S);
    bfs(arr[x][k].F);
    if(ans.back()==-1)return;
    ans.PB(arr[x][k].S);
    return;
  }
  int k=0;
  if(vis[arr[x][k].F])k++;
  int z=arr[x][k].S;
  int y=-1;
  for(auto u:arr[arr[x][k].F])if(u.F==x)y=u.S;
  k++;
  if(vis[arr[x][k].F])k++;
  int c=arr[x][k].S;
  int d=-1;
  for(auto u:arr[arr[x][k].F])if(u.F==x)d=u.S;
  ans.PB(z);ans.PB(y);ans.PB(c);ans.PB(d);ans.PB(y);ans.PB(z);ans.PB(d);ans.PB(c);
  return;
}

std::variant<bool, std::vector<int>> find_journey(
    int N, int M, std::vector<int> U, std::vector<int> V) {
  n=N;m=M;
  if(n==2){
    if(m<=2)return false;
    vi a;
    REP(i,0,m)if(U[i]==0)a.PB(i);
    int p=-1;
    REP(i,0,m)if(U[i]!=0)p=i;
    int k=a.size();
    if(k<2||p==-1)return false;
    ans.PB(a[0]);ans.PB(p);ans.PB(a[1]);ans.PB(a[0]);ans.PB(p);ans.PB(a[1]);
    return ans;
  }
  arr.resize(n);
  REP(i,0,m)arr[U[i]].PB({V[i],i});
  if(arr[0].size()>=2){
    int x=arr[0][0].S;
    int y=-1;
    for(auto u:arr[arr[0][0].F])if(u.F==0)y=u.S;
    int c=arr[0][1].S;
    int d=-1;
    for(auto u:arr[arr[0][1].F])if(u.F==0)d=u.S;
    ans.PB(x);ans.PB(y);ans.PB(c);ans.PB(d);ans.PB(y);ans.PB(x);ans.PB(d);ans.PB(c);
    return ans;
  }
  if(arr[0].empty())return false;
  vis.resize(n,0);
  vis[0]=1;
  ans.PB(arr[0][0].S);
  bfs(arr[0][0].F);
  if(ans.back()==-1)return false;
  ans.PB(arr[0][0].S);
  return ans;
}

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 7.35 / 21
• Subtask 4: 0 / 24
• Subtask 5: 0 / 45