Submission #960007

#	Time	Username	Problem	Language	Result	Execution time	Memory
960007		LucaLucaM	Paint By Numbers (IOI16_paint)	C++17	80 / 100	2057 ms	4696 KiB

paint

#include "paint.h"

#include <cstdlib>
#include <functional>
#include <iostream>
#include <cassert>

#define debug(x) #x << " = " << x << '\n'

const int NMAX = 2e5 + 2;
const int KMAX = 100;

bool pref[NMAX + 1][KMAX + 1][2];
bool suff[NMAX + 1][KMAX + 1][2];
int sumX[NMAX + 1];
int sum_[NMAX + 1];

bool makeX(int l, int r) {
  return sum_[r] - sum_[l - 1] == 0;
}

bool make_(int l, int r) {
  return sumX[r] - sumX[l - 1] == 0;
}

std::string solve_puzzle(std::string s, std::vector<int> c) {
  int n = (int) s.size();
  int k = (int) c.size();
  s = '$' + s;
  c.insert(c.begin(), 0);
  std::string answer(n, '.');


  std::function<void()> recalc = [&] () -> void {
    for (int i = 1; i <= n; i++) {
      sumX[i] = sumX[i - 1] + (s[i] == 'X'? +1 : 0);
      sum_[i] = sum_[i - 1] + (s[i] == '_'? +1 : 0);
    }
    pref[0][0][0] = pref[0][0][1] = true;

    for (int i = 1; i <= n; i++) {
      for (int j = 0; j <= k; j++) {
        pref[i][j][0] = pref[i][j][1] = false;
      }
      if (s[i] == 'X') {
        for (int j = 0; j <= k; j++) {
          if (j != 0 && i - c[j] >= 0) {
            pref[i][j][1] |= (pref[i - c[j]][j - 1][0] & makeX(i - c[j] + 1, i));
          }
        }
      } else if (s[i] == '_') {
        for (int j = 0; j <= k; j++) {
          pref[i][j][0] |= pref[i - 1][j][0];
          pref[i][j][0] |= pref[i - 1][j][1];
        }
      } else {
        for (int j = 0; j <= k; j++) {
          pref[i][j][0] |= pref[i - 1][j][0];
          pref[i][j][0] |= pref[i - 1][j][1];
          if (j != 0 && i - c[j] >= 0) {
            pref[i][j][1] |= (pref[i - c[j]][j - 1][0] & makeX(i - c[j] + 1, i));
          }
        }
      }
    }
  };

  std::function<bool()> works = [&] () -> bool {
    return pref[n][k][0] | pref[n][k][1];
  };

  recalc();
  assert(works());

  for (int i = 1; i <= n; i++) {
    if (s[i] != '.') {
      answer[i - 1] = s[i];
      continue;
    }

    bool worksX, works_;
    s[i] = 'X';
    recalc();
    worksX = works();


    s[i] = '_';
    recalc();
    works_ = works();
//    if (i == 3) {
//      std::cout << debug(works_) << debug(n) << debug(k);
//      std::cout << debug(pref[n][2][0]);
//    }
    s[i] = '.';


    if (worksX && works_) {
      answer[i - 1] = '?';
    } else if (worksX) {
      answer[i - 1] = 'X';
    } else {
      answer[i - 1] = '_';
    }
  }

//  std::cout << debug(s) << '\n';

  return answer;
}

/**


..........
2 3 4

........
2 3 4

..._._....
1 3

.X........
1 3


**/

• Subtask 1: 7 / 7
• Subtask 2: 3 / 3
• Subtask 3: 22 / 22
• Subtask 4: 27 / 27
• Subtask 5: 21 / 21
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10