제출 #572602

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
572602		cjoa	장난감 기차 (IOI17_train)	C++14	100 / 100	743 ms	1456 KiB

train

#include "train.h"
#include <queue>
#include <algorithm>

#include <iostream>
#include <cassert>

using namespace std;

using VI = vector<int>;
using VVI = vector<VI>;

enum Player {
   Arezou = 1, Borzou = 0
};

enum State {
   UNKNOWN = -1, LOSING = 0, POSSIBLY_WINNING = 1
};


int N, M;
VVI G;
VI in_deg;
VI owner;

void bfs(int player, const VI& sources, vector<int>& states) {
   queue<int> q;
   for (int i : sources)
      q.push(i);

   VI num_neighbors_required(G.size());
   for (int i = 0; i < N; i++) {
      if (states[i] == UNKNOWN) {
         if (owner[i] == player)
            num_neighbors_required[i] = 1;
         else
            num_neighbors_required[i] = in_deg[i];
      }
   }

   while (!q.empty()) {
      int cur = q.front(); q.pop();
      for (int nxt : G[cur]) {
         if (states[nxt] != UNKNOWN)
            continue;
         num_neighbors_required[nxt]--;
         if (num_neighbors_required[nxt] == 0) {
            q.push(nxt);
            states[nxt] = player == Arezou ? POSSIBLY_WINNING : LOSING;
         }
      }
   }
}

std::vector<int> who_wins(std::vector<int> a, std::vector<int> r,
                          std::vector<int> u, std::vector<int> v)
{
   owner = a;

   N = a.size();
   M = u.size();
   assert( (int) v.size() == M );
   
   // Build transpose graph G (that is, reverse each edge)
   G = VVI(N);
   in_deg = VI(N);
   for (int j = 0; j < M; ++j) {
      G[ v[j] ].push_back( u[j] );
      in_deg[ u[j] ]++;
   }

   vector<int> states(N, UNKNOWN);
   for (int ronda = 1; ronda <= 10000; ronda++) {
      VI sources;
      for (int i = 0; i < N; i++)
         if (r[i] == 1 and states[i] != LOSING) {
            sources.push_back(i);
            states[i] = POSSIBLY_WINNING;
         }

      bfs(Arezou, sources, states);

/*
      cerr << "Round #" << ronda << endl;
      for (int i = 0; i < N; i++)
         cerr << states[i] << ' ';
      cerr << endl;
*/

      if (count(states.begin(), states.end(), UNKNOWN) == 0)
         break;

      sources.clear();
      for (int i = 0; i < N; i++) {
         switch (states[i]) {
            case UNKNOWN:
               states[i] = LOSING;
            case LOSING:
               sources.push_back(i);
               break;
            case POSSIBLY_WINNING:
               states[i] = UNKNOWN;
               break;
         }
      }

      bfs(Borzou, sources, states);

/*
      for (int i = 0; i < N; i++)
         cerr << states[i] << ' ';
      cerr << endl;
*/

      if (count(states.begin(), states.end(), UNKNOWN) == 0)
         break;

   }

   VI res(N);
   for (int i = 0; i < N; i++) {
      assert( states[i] != UNKNOWN );
      if (states[i] == LOSING)
         res[i] = 0;
      else
         res[i] = 1;
   }

   return res;
}

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 11 / 11
• Subtask 4: 11 / 11
• Subtask 5: 12 / 12
• Subtask 6: 51 / 51