Problem p03225 (C++)

Buggy submission (status: Runtime Error):
/*
:>
*/
#pragma GCC optimize("O3")
#pragma GCC target("sse4")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;

random_device(rd);
mt19937 rng(rd());
const long long FIXED_RANDOM =
    chrono::steady_clock::now().time_since_epoch().count();

struct custom_hash {
  template <class T> unsigned long long operator()(T v) const {
    unsigned long long x = v;
    x += FIXED_RANDOM;
    x += 11400714819323198485ull;
    x = (x ^ (x >> 30)) * 13787848793156543929ull;
    x = (x ^ (x >> 27)) * 10723151780598845931ull;
    return x ^ (x >> 31);
  }
};

template <class T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template <class T, class U> using hash_table = gp_hash_table<T, U, custom_hash>;

template <class T> void readi(T &x) {
  x = 0;
  bool negative = false;
  char c = ' ';
  while (c < '-') {
    c = getchar();
  }
  if (c == '-') {
    negative = true;
    c = getchar();
  }
  while (c >= '0') {
    x = x * 10 + (c - '0');
    c = getchar();
  }
  if (negative) {
    x = -x;
  }
}
template <class T> void printi(T output) {
  if (output == 0) {
    putchar('0');
    return;
  }
  if (output < 0) {
    putchar('-');
    output = -output;
  }
  int buf[20], n = 0;
  while (output) {
    buf[n] = ((output % 10));
    output /= 10;
    n++;
  }
  for (n--; n >= 0; n--) {
    putchar(buf[n] + '0');
  }
  return;
}
template <class T> void ckmin(T &a, T b) { a = min(a, b); }
template <class T> void ckmax(T &a, T b) { a = max(a, b); }
long long expo(long long a, long long e, long long mod) {
  return ((e == 0)
              ? 1
              : ((expo(a * a % mod, e >> 1, mod)) * ((e & 1) ? a : 1) % mod));
}
template <class T, class U> T nmod(T &x, U mod) {
  if (x >= mod)
    x -= mod;
}
template <class T> T gcd(T a, T b) { return (b ? gcd(b, a % b) : a); }
template <class T> T randomize(T mod) {
  return (uniform_int_distribution<T>(0, mod - 1))(rng);
}

#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define PF push_front
#define fi first
#define se second
#define debug(x) cerr << #x << " = " << x << endl;
#define sz(x) ((int)(x.size()))

const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-9;

#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 613

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;

int N, M;
bitset<MAXN> grid[MAXN];
int ans;
int vsum[MAXN][MAXN], hsum[MAXN][MAXN];

bool chk(int x, int y) {
  return (0 <= x && x < N && 0 <= y && y < N && grid[x][y]);
}
int vertsum(int y, int l, int r) {
  if (l > r || l >= N || r < 0)
    return 0;
  ckmax(y, 0);
  ckmin(y, N - 1);
  ckmax(l, 0);
  ckmin(l, N - 1);
  ckmax(r, 0);
  ckmin(r, N - 1);
  return vsum[r + 1][y] - vsum[l][y];
}
int horzsum(int x, int l, int r) {
  if (l > r || l >= N || r < 0)
    return 0;
  ckmax(x, 0);
  ckmin(x, N - 1);
  ckmax(l, 0);
  ckmin(l, N - 1);
  ckmax(r, 0);
  ckmin(r, N - 1);
  return hsum[x][r + 1] - hsum[x][l];
}

int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  // cout << fixed << setprecision(10);
  // cerr << fixed << setprecision(10);
  // freopen ("file.in", "r", stdin);
  // freopen ("file.out", "w", stdout);
  cin >> N >> M;
  for (int i = 0; i < N; i++) {
    string temps;
    cin >> temps;
    for (int j = 0; j < M; j++) {
      grid[i + j][i - j + M - 1] = (bool)(temps[j] == '#');
    }
  }
  N = N + M - 1;
  // for (int i = 0; i < N; i++)
  // {
  // 	for (int j = 0; j < N; j++)
  // 	{
  // 		cerr << grid[i][j];
  // 	}
  // 	cerr << endl;
  // }
  for (int k = 2; k <= N; k += 2) {
    for (int i = 0; i <= N; i++) {
      for (int j = 0; j <= N; j++) {
        vsum[i][j] = 0;
        hsum[i][j] = 0;
      }
    }
    for (int i = 0; i < N; i++) {
      for (int j = 0; j < N; j++) {
        vsum[i + 1][j] = vsum[i][j] + (bool)(grid[i][j] & grid[i + k][j]);
        hsum[i][j + 1] = hsum[i][j] + (bool)(grid[i][j] & grid[i][j + k]);
      }
    }
    for (int i = 0; i < N; i++) {
      for (int j = 0; j < N; j++) {
        if (!grid[i][j])
          continue;
        ans += horzsum(i - k, j - k, j - 1);
        ans += horzsum(i + k, j - k + 1, j);
        ans += vertsum(j - k, i - k + 1, i);
        ans += vertsum(j + k, i - k, i - 1);
      }
    }
  }
  // we win!
  cout << ans << '\n';
  // cerr << "time elapsed = " << (clock() / (CLOCKS_PER_SEC / 1000)) << " ms"
  // << endl;
  return 0;
}


Fixed submission:
/*
:>
*/
#pragma GCC optimize("O3")
#pragma GCC target("sse4")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;

random_device(rd);
mt19937 rng(rd());
const long long FIXED_RANDOM =
    chrono::steady_clock::now().time_since_epoch().count();

struct custom_hash {
  template <class T> unsigned long long operator()(T v) const {
    unsigned long long x = v;
    x += FIXED_RANDOM;
    x += 11400714819323198485ull;
    x = (x ^ (x >> 30)) * 13787848793156543929ull;
    x = (x ^ (x >> 27)) * 10723151780598845931ull;
    return x ^ (x >> 31);
  }
};

template <class T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template <class T, class U> using hash_table = gp_hash_table<T, U, custom_hash>;

template <class T> void readi(T &x) {
  x = 0;
  bool negative = false;
  char c = ' ';
  while (c < '-') {
    c = getchar();
  }
  if (c == '-') {
    negative = true;
    c = getchar();
  }
  while (c >= '0') {
    x = x * 10 + (c - '0');
    c = getchar();
  }
  if (negative) {
    x = -x;
  }
}
template <class T> void printi(T output) {
  if (output == 0) {
    putchar('0');
    return;
  }
  if (output < 0) {
    putchar('-');
    output = -output;
  }
  int buf[20], n = 0;
  while (output) {
    buf[n] = ((output % 10));
    output /= 10;
    n++;
  }
  for (n--; n >= 0; n--) {
    putchar(buf[n] + '0');
  }
  return;
}
template <class T> void ckmin(T &a, T b) { a = min(a, b); }
template <class T> void ckmax(T &a, T b) { a = max(a, b); }
long long expo(long long a, long long e, long long mod) {
  return ((e == 0)
              ? 1
              : ((expo(a * a % mod, e >> 1, mod)) * ((e & 1) ? a : 1) % mod));
}
template <class T, class U> T nmod(T &x, U mod) {
  if (x >= mod)
    x -= mod;
}
template <class T> T gcd(T a, T b) { return (b ? gcd(b, a % b) : a); }
template <class T> T randomize(T mod) {
  return (uniform_int_distribution<T>(0, mod - 1))(rng);
}

#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define PF push_front
#define fi first
#define se second
#define debug(x) cerr << #x << " = " << x << endl;
#define sz(x) ((int)(x.size()))

const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-9;

#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 1213

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;

int N, M;
bitset<MAXN> grid[MAXN];
int ans;
int vsum[MAXN][MAXN], hsum[MAXN][MAXN];

bool chk(int x, int y) {
  return (0 <= x && x < N && 0 <= y && y < N && grid[x][y]);
}
int vertsum(int y, int l, int r) {
  if (l > r || l >= N || r < 0)
    return 0;
  ckmax(y, 0);
  ckmin(y, N - 1);
  ckmax(l, 0);
  ckmin(l, N - 1);
  ckmax(r, 0);
  ckmin(r, N - 1);
  return vsum[r + 1][y] - vsum[l][y];
}
int horzsum(int x, int l, int r) {
  if (l > r || l >= N || r < 0)
    return 0;
  ckmax(x, 0);
  ckmin(x, N - 1);
  ckmax(l, 0);
  ckmin(l, N - 1);
  ckmax(r, 0);
  ckmin(r, N - 1);
  return hsum[x][r + 1] - hsum[x][l];
}

int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  // cout << fixed << setprecision(10);
  // cerr << fixed << setprecision(10);
  // freopen ("file.in", "r", stdin);
  // freopen ("file.out", "w", stdout);
  cin >> N >> M;
  for (int i = 0; i < N; i++) {
    string temps;
    cin >> temps;
    for (int j = 0; j < M; j++) {
      grid[i + j][i - j + M - 1] = (bool)(temps[j] == '#');
    }
  }
  N = N + M - 1;
  // for (int i = 0; i < N; i++)
  // {
  // 	for (int j = 0; j < N; j++)
  // 	{
  // 		cerr << grid[i][j];
  // 	}
  // 	cerr << endl;
  // }
  for (int k = 2; k <= N; k += 2) {
    for (int i = 0; i <= N; i++) {
      for (int j = 0; j <= N; j++) {
        vsum[i][j] = 0;
        hsum[i][j] = 0;
      }
    }
    for (int i = 0; i < N; i++) {
      for (int j = 0; j < N; j++) {
        vsum[i + 1][j] = vsum[i][j] + (bool)(grid[i][j] & grid[i + k][j]);
        hsum[i][j + 1] = hsum[i][j] + (bool)(grid[i][j] & grid[i][j + k]);
      }
    }
    for (int i = 0; i < N; i++) {
      for (int j = 0; j < N; j++) {
        if (!grid[i][j])
          continue;
        ans += horzsum(i - k, j - k, j - 1);
        ans += horzsum(i + k, j - k + 1, j);
        ans += vertsum(j - k, i - k + 1, i);
        ans += vertsum(j + k, i - k, i - 1);
      }
    }
  }
  // we win!
  cout << ans << '\n';
  // cerr << "time elapsed = " << (clock() / (CLOCKS_PER_SEC / 1000)) << " ms"
  // << endl;
  return 0;
}