Submission #792203

#	Time	Username	Problem	Language	Result	Execution time	Memory
792203		cig32	Dijamant (COCI22_dijamant)	C++17	70 / 70	388 ms	116572 KiB

Main

#include "bits/stdc++.h"
using namespace std;
const int MAXN = 4e6 + 10;
const int MOD = 1e9 + 7;
#define int int
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
int rnd(int x, int y) {
  int u = uniform_int_distribution<int>(x, y)(rng); return u;
}
int bm(int b, int p) { // bigmod
    if(p==0) return 1;
    int r = bm(b, p/2);
    if(p&1) return (((r*r) % MOD) * b) % MOD;
    return (r*r) % MOD;
}
int inv(int b) { // modinv
    return bm(b, MOD-2);
}
int f[MAXN];
int nCr(int n, int r) { // nCr main function, requires precomputation function
    int ans = f[n]; ans *= inv(f[r]); ans %= MOD;
    ans *= inv(f[n-r]); ans %= MOD; return ans;
}
void precomp() { // factorials for nCr, function MUST BE CALLED
    f[0] = 1;
    for(int i=1; i<MAXN; i++) f[i] = (f[i-1] * i) % MOD;
}
int dsu[MAXN];
int set_of(int u) {
  if(dsu[u] == u) return u;
  return dsu[u] = set_of(dsu[u]);
}
void union_(int u, int v) {
  dsu[set_of(u)] = set_of(v);
}
void solve(int tc) {
  int n, m;
  cin >> n >> m;
  for(int i=1; i<=n*m; i++) dsu[i] = i;
  char a[n+1][m+1];
  for(int i=1; i<=n; i++) {
    for(int j=1; j<=m; j++) {
      cin >> a[i][j];
    }
  }
  for(int i=1; i<=n; i++) {
    for(int j=1; j<=m; j++) {
      if(i < n && a[i][j] == '.' && a[i+1][j] == '.' && set_of((i-1) * m + j) != set_of(i * m + j)) union_((i-1) * m + j, i * m + j);
      if(j < m && a[i][j] == '.' && a[i][j+1] == '.' && set_of((i-1) * m + j) != set_of((i-1) * m + j + 1)) union_((i-1) * m + j, (i-1) * m + j + 1); 
    }
  }
  int sz[n * m + 1];
  for(int i=1; i<=n * m; i++) sz[i] = 0;
  for(int i=1; i<=n * m; i++) sz[set_of(i)]++;
  int plus[n+2][m+2], minus[n+2][m+2];
  int hor[n+2][m+2], ver[n+2][m+2];
  for(int i=0; i<=n+1; i++) {
    for(int j=0; j<=m+1; j++) {
      plus[i][j] = minus[i][j] = hor[i][j] = ver[i][j] = 0;
    }
  }
  for(int i=1; i<=n; i++) {
    for(int j=1; j<=m; j++) {
      plus[i][j] = plus[i-1][j+1] + (a[i][j] == '#');
      minus[i][j] = minus[i-1][j-1] + (a[i][j] == '#');
      hor[i][j] = hor[i][j-1] + (a[i][j] == '#');
      ver[i][j] = ver[i-1][j] + (a[i][j] == '#');
    }
  }
  int ans = 0;
  for(int i=2; i<n; i++) {
    for(int j=2; j<m; j++) {
      if(a[i][j] == '#') continue;
      int lb = 0, rb = j;
      int len;
      while(lb < rb) {
        int mid = (lb + rb + 1) >> 1;
        if(hor[i][j] - hor[i][mid] == 0) rb = mid - 1;
        else lb = mid;
      }
      if(hor[i][j] - hor[i][lb] == 1) {
        len = j - lb - 1; // dist between corner and centre
      }
      if(j + len > m) continue;
      if(i + len > n) continue;
      if(i - len < 1) continue;
      if(hor[i][j + len] - hor[i][j] == 1 && a[i][j + len] == '#') {
        if(ver[i + len][j] - ver[i][j] == 1 && a[i + len][j] == '#') {
          if(ver[i - 1][j] - ver[i - len - 1][j] == 1 && a[i - len][j] == '#') {
            if(a[i][j - len] == '#') {
              if(minus[i][j + len] - minus[i - len][j] == len) {
                if(plus[i + len][j] - plus[i][j + len] == len) {
                  if(minus[i + len][j] - minus[i][j - len] == len) {
                    if(plus[i][j - len] - plus[i - len][j] == len) {
                      if(sz[set_of((i-1) * m + j)] == len*len + (len-1) * (len-1)) {
                        ans++;
                      } 
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
  cout << ans << "\n";
}
int32_t main(){
  precomp();
  ios::sync_with_stdio(0); cin.tie(0);
  int t = 1; //cin >> t;
  for(int i=1; i<=t; i++) solve(i);
}  

Compilation message (stderr)

Main.cpp: In function 'void solve(int)':
Main.cpp:93:19: warning: 'len' may be used uninitialized in this function [-Wmaybe-uninitialized]
   93 |                   if(minus[i + len][j] - minus[i][j - len] == len) {
      |                   ^~

• Subtask 1: 20 / 20
• Subtask 2: 50 / 50