Submission #296766

#	Time	Username	Problem	Language	Result	Execution time	Memory
296766		Bruteforceman	Seats (IOI18_seats)	C++11	100 / 100	3576 ms	173944 KiB

seats

#include "bits/stdc++.h"
#include "seats.h"
using namespace std;
const int maxn = 1e6 + 10;
vector <vector <int>> a;
vector <vector <bool>> can;
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);
}
struct node {
  int val, cnt;
  int lazy;
  void add(int x) {
    val += x;
    lazy += x;
  }
} t[maxn * 4];
void pushdown(int c) {
  if(!t[c].lazy) return ;
  int l = c << 1;
  int r = l + 1;
  t[l].add(t[c].lazy);
  t[r].add(t[c].lazy);
  t[c].lazy = 0;
}
void build(int c = 1, int b = 0, int e = h * w - 1) {
  t[c].val = t[c].lazy = 0;
  t[c].cnt = e - b + 1;
  if(b == e) return ;
  int m = (b + e) >> 1;
  int l = c << 1;
  int r = l + 1;
  build(l, b, m);
  build(r, m + 1, e);
}
void add(int x, int y, int val, int c = 1, int b = 0, int e = h * w - 1) {
  if(x > y) return ;
  if(x <= b && e <= y) {
    t[c].add(val);
    return ;
  }
  if(y < b || e < x) return ;
  pushdown(c);
  int m = (b + e) >> 1;
  int l = c << 1;
  int r = l + 1;
  add(x, y, val, l, b, m);
  add(x, y, val, r, m + 1, e);
  t[c].val = min(t[l].val, t[r].val);
  t[c].cnt = 0;
  if(t[c].val == t[l].val) t[c].cnt += t[l].cnt;
  if(t[c].val == t[r].val) t[c].cnt += t[r].cnt;
}
void process(int x, int y, int val) {
  for(int dx : {-1, 1}) {
    for(int dy : {-1, 1}) {
      if(dx == -1 && dy == -1) continue;
      if(inside(x + dx, y) && !can[x + dx][y] && 
         inside(x, y + dy) && !can[x][y + dy] && !can[x][y]) continue;
      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);
      if(dx != 1 || dy != 1) continue;
      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));
  can = vector <vector <bool>> (H, vector <bool> (W, true));
  row = R;
  col = C;
  for(int i = 0; i < H * W; i++) {
    a[row[i]][col[i]] = i;
  }
  build();
  for(int i = 0; i < h; i++) {
    for(int j = 0; j < w; j++) {
      process(i, j, 1);
    }
  }
  for(int i = 0; i < h; i++) {
    for(int j = 0; j < w; j++) {
      can[i][j] = false;
    }
  }
}
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]));
  can[row[p]][col[p]] = can[row[q]][col[q]] = true;
  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);  
  }
  can[row[p]][col[p]] = can[row[q]][col[q]] = false; 
  return t[1].cnt;
}

Compilation message (stderr)

seats.cpp: In function 'int swap_seats(int, int)':
seats.cpp:104:7: warning: unused variable 'ans' [-Wunused-variable]
  104 |   int ans = 0;
      |       ^~~

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