Submission #296732

#	Time	Username	Problem	Language	Result	Execution time	Memory
296732		Bruteforceman	Seats (IOI18_seats)	C++11	11 / 100	4100 ms	48820 KiB

seats

#include "bits/stdc++.h"
#include "seats.h"
using namespace std;
const int maxn = 1e6 + 10;
vector <vector <int>> a;
vector <int> row, col;
int h, w;
int arr[maxn];

bool inside(int x, int y) {
  return (0 <= x && x < h) && (0 <= y && y < w);
}
bool isOkay(int R) {
  int total = 0;
  for(int i = 0; i <= R; i++) {
    for(int dx : {-1, 1}) {
      for(int dy : {-1, 1}) {
        int x = row[i];
        int y = col[i];
        int cnt = 0;
        if(!inside(x + dx, y) || a[x + dx][y] > R) ++cnt;
        if(!inside(x, y + dy) || a[x][y + dy] > R) ++cnt;
        if(cnt == 2) ++total;
      }
    }
  }
  for(int i = R + 1; i < h * w; i++) {
    for(int dx : {-1, 1}) {
      for(int dy : {-1, 1}) {
        int x = row[i];
        int y = col[i];
        int cnt = 0;
        if(inside(x + dx, y) && a[x + dx][y] <= R) ++cnt;
        if(inside(x, y + dy) && a[x][y + dy] <= R) ++cnt;
        if(cnt == 2) ++total;
      }
    }
  }
  return (total == 4);
}
void add(int x, int y, int val) {
  for(int i = x; i <= y; i++) arr[i] += val;
}
void process(int x, int y, int val) {
  for(int dx : {-1, 1}) {
    for(int dy : {-1, 1}) {
      int r = h * w;
      if(inside(x + dx, y)) r = min(r, a[x + dx][y]);
      if(inside(x, y + dy)) r = min(r, a[x][y + dy]);
      add(a[x][y], r - 1, val);
      r = 0;
      if(inside(x + dx, y)) r = max(r, a[x + dx][y]);
      else r = h * w;
      if(inside(x, y + dy)) r = max(r, a[x][y + dy]);
      else r = h * w;
      add(r, a[x][y] - 1, val);
    }
  }
}
void give_initial_chart(int H, int W, std::vector<int> R, std::vector<int> C) {
  h = H;
  w = W;
  a = vector <vector <int>> (H, vector <int> (W, 0));
  row = R;
  col = C;
  for(int i = 0; i < H * W; i++) {
    a[row[i]][col[i]] = i;
  }
  fill(arr, arr + (h * w), 0);
  for(int i = 0; i < h; i++) {
    for(int j = 0; j < w; j++) {
      process(i, j, 1);
    }
  }
}
const int dx[] = {0, 0, -1, 1};
const int dy[] = {-1, 1, 0, 0};

int swap_seats(int p, int q) {
  int ans = 0;
  set <pair <int, int>> change;
  change.insert(make_pair(row[p], col[p]));
  change.insert(make_pair(row[q], col[q]));
  for(int i = 0; i < 4; i++) {
    int x = row[p] + dx[i];
    int y = col[p] + dy[i];
    if(inside(x, y)) change.insert(make_pair(x, y));
  }
  for(int i = 0; i < 4; i++) {
    int x = row[q] + dx[i];
    int y = col[q] + dy[i];
    if(inside(x, y)) change.insert(make_pair(x, y));
  }
  for(auto i : change) {
    process(i.first, i.second, -1);  
  }
  swap(a[row[p]][col[p]], a[row[q]][col[q]]);
  swap(row[p], row[q]);
  swap(col[p], col[q]);
  for(auto i : change) {
    process(i.first, i.second, 1);  
  }
  return count(arr, arr + (h * w), 4);
}

Compilation message (stderr)

seats.cpp: In function 'int swap_seats(int, int)':
seats.cpp:80:7: warning: unused variable 'ans' [-Wunused-variable]
   80 |   int ans = 0;
      |       ^~~

• Subtask 1: 5 / 5
• Subtask 2: 6 / 6
• Subtask 3: 0 / 20
• Subtask 4: 0 / 6
• Subtask 5: 0 / 33
• Subtask 6: 0 / 30