Submission #205055

#	Time	Username	Problem	Language	Result	Execution time	Memory
205055		WLZ	Paint By Numbers (IOI16_paint)	C++14	100 / 100	700 ms	173732 KiB

paint

#include "paint.h"
#include <bits/stdc++.h>
using namespace std;

string solve_puzzle(string s, vector<int> c) {
  int n = (int) s.length(), k = (int) c.size();
  c.insert(c.begin(), 0);
  s = '$' + s + '$';
  vector< vector<int> > pre(n + 1, vector<int>(2, 0));
  for (int i = 1; i <= n; i++) {
    if (s[i] == '_') {
      pre[i][0] = 1;
    } else if (s[i] == 'X') {
      pre[i][1] = 1;
    }
    pre[i][0] += pre[i - 1][0];
    pre[i][1] += pre[i - 1][1];
  }
  vector< vector<int> > dp_left(k + 1, vector<int>(n + 1, 0)), dp_right(k + 2, vector<int>(n + 2, 0));
  for (int j = 0; j <= n; j++) {
    dp_left[0][j] = (pre[j][1] == 0);
  }
  for (int i = 1; i <= k; i++) {
    for (int j = 1; j <= n; j++) {
      int b1 = dp_left[i][j - 1];
      int b2 = (j - c[i] >= 0 && pre[j][0] - pre[j - c[i]][0] == 0 && s[j - c[i]] != 'X');
      if (i == 1) {
        if (j - c[i] >= 1) {
          b2 = b2 && dp_left[i - 1][j - c[i] - 1];
        }
      } else {
        b2 = b2 && (j - c[i] >= 1 && dp_left[i - 1][j - c[i] - 1]);
      }
      if (s[j] == 'X') {
        dp_left[i][j] = b2;
      } else if (s[j] == '_') {
        dp_left[i][j] = b1;
      } else {
        dp_left[i][j] = b1 || b2;
      }
    }
  }
  for (int j = n; j >= 1; j--) {
    dp_right[k + 1][j] = (pre[n][1] - pre[j - 1][1] == 0);
  }
  dp_right[k + 1][0] = (pre[n][1] == 0);
  dp_right[k + 1][n + 1] = 1;
  for (int i = k; i >= 1; i--) {
    for (int j = n; j >= 1; j--) {
      int b1 = dp_right[i][j + 1];
      int b2 = (j + c[i] <= n + 1 && pre[j + c[i] - 1][0] - pre[j - 1][0] == 0 && s[j + c[i]] != 'X');
      if (i == k) {
        if (j + c[i] <= n) {
          b2 = b2 && dp_right[i + 1][j + c[i] + 1];
        }
      } else {
        b2 = b2 && (j + c[i] <= n && dp_right[i + 1][j + c[i] + 1]);
      }
      if (s[j] == 'X') {
        dp_right[i][j] = b2;
      } else if (s[j] == '_') {
        dp_right[i][j] = b1;
      } else {
        dp_right[i][j] = b1 || b2;
      }
    }
  }
  vector<int> white(n + 1), black(n + 1);
  for (int j = 1; j <= n; j++) {
    if (s[j] == 'X') {
      white[j] = 0;
      continue;
    }
    if (s[j] == '_') {
      white[j] = 1;
      continue;
    }
    for (int i = 0; i <= k; i++) {
      if (dp_left[i][j - 1] && dp_right[i + 1][j + 1]) {
        white[j] = 1;
        break;
      }
    }
  }
  for (int i = 1; i <= k; i++) {
    vector<int> tmp(n + 1, 0);
    for (int j = 1; j + c[i] - 1 <= n; j++) {
      if (s[j - 1] == 'X' || s[j + c[i]] == 'X') {
        continue;
      }
      if (pre[j + c[i] - 1][0] - pre[j - 1][0] > 0) {
        continue;
      }
      int b1, b2;
      if (j == 1) {
        b1 = (i == 1);
      } else {
        b1 = dp_left[i - 1][j - 2];
      }
      if (j + c[i] - 1 == n) {
        b2 = (i == k);
      } else {
        b2 = dp_right[i + 1][j + c[i] + 1];
      }
      if (b1 && b2) {
        for (int t = j + c[i] - 1; t >= j && !tmp[t]; t--) {
          tmp[t] = 1;
        }
      }
    }
    for (int i = 1; i <= n; i++) {
      black[i] = black[i] || tmp[i];
    }
  }
  for (int i = 1; i <= n; i++) {
    if (s[i] == '.') {
      if (white[i] && black[i]) {
        s[i] = '?';
      } else if (white[i] && !black[i]) {
        s[i] = '_';
      } else if (!white[i] && black[i]) {
        s[i] = 'X';
      }
    }
  }
  return s.substr(1, n);
}

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