Submission #628850

#	Time	Username	Problem	Language	Result	Execution time	Memory
628850		c28dnv9q3	Prisoner Challenge (IOI22_prison)	C++17	60 / 100	16 ms	1148 KiB

prison

#include "prison.h"
#include <vector>
#include <cstdio>

using namespace std;

struct State {
  int bitn;
  int isset;
};

int N;

int encode(State s) {
  int v = (s.bitn << 1) | (s.isset << 0);
  // printf("%d %d\n", s.bitn, v);
  return v;
}
State decode(int v) {
  State s;
  s.isset = (v >> 0) & 1;
  s.bitn = v >> 1;
  return s;
}

vector<vector<int>> devise_strategy(int N) {
  ::N = N;
  int Q = 25;
  vector<vector<int>> s(Q+1, vector<int>(N+1));
  
  s[0][0] = 0; // inspect bag A
  for (int i = 1; i <= N; i++) {
    State p{};
    p.bitn = 12;
    p.isset = (i & (1 << p.bitn)) ? 1 : 0;
    s[0][i] = encode(p);
  }
  
  for (int i = 1; i < s.size(); i++) {
    // when sees i on board
    State pi = decode(i);
    int t = 1-(pi.bitn&1);
    s[i][0] = t; // inspect bag A/B
    for (int j = 1; j <= N; j++) {
      // j in bag A/B
      bool b = j & (1 << pi.bitn);
      if (b && !pi.isset) {
        s[i][j] = t ? -1 : -2; // other has less
      } else if (!b && pi.isset) {
        s[i][j] = t ? -2 : -1; // this has less
      } else if (pi.bitn == 0) {
        s[i][j] = -1; // shouldn't happen
      } else {
        State p;
        p.bitn = pi.bitn - 1;
        p.isset = (j & (1 << p.bitn)) ? 1 : 0;
        s[i][j] = encode(p);
        if (s[i][j] == 0) {
          s[i][j] = t ? -2 : -1; // this has less
        }
      }
    }
  }

  return s;
}

Compilation message (stderr)

prison.cpp: In function 'std::vector<std::vector<int> > devise_strategy(int)':
prison.cpp:39:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |   for (int i = 1; i < s.size(); i++) {
      |                   ~~^~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 50 / 90