Problem p03157 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
using plll = pair<ll, pll>;
using graph = vector<vector<int>>;

const ll MOD = 1000000007;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

ll abs1(ll a) {
  if (a >= 0)
    return a;
  else
    return -a;
}

ll pow1(ll a, ll b, ll p = LLONG_MAX) {
  ll ret = 1;
  while (b != 0) {
    if ((b & 1) == 1) {
      ret *= a;
    }
    a *= a;
    if (a >= p)
      a %= p;
    b = b >> 1;
  }
  return ret;
}

int digit(ll a, ll b) {
  int i = 0;
  while (a != 0) {
    a /= b;
    i++;
  }
  return i;
}

ll gcd1(ll a, ll b) {
  if (a == 0 && b == 0)
    return 0;
  ll n;
  while (a % b != 0) {
    n = a % b;
    a = b;
    b = n;
  }
  return b;
}

ll solveLinear(ll n, ll m, ll c) {
  if (n == 0 && m == 0)
    return 0;
  ll a[100], b[100];
  a[0] = n;
  b[0] = m;
  int i = 1;
  while (b[i - 1] != 0) {
    a[i] = b[i - 1];
    b[i] = a[i - 1] % b[i - 1];
    i++;
  }
  n = i;
  if (c % a[n - 1] != 0) {
    return 0;
  }
  ll x = c / a[n - 1], y = 0;
  for (i = 1; i < n; i++) {
    ll cnt = x;
    x = y;
    y = cnt - (a[n - i - 1] / b[n - i - 1]) * y;
  }
  return x;
}

ll modInv(ll a, ll p = MOD) {
  a %= p;
  ll n = solveLinear(a, p, 1);
  n %= p;
  if (n < 0)
    return n + p;
  return n;
}

ll fact(ll n, ll p = MOD) {
  if (n < 0)
    return 0;
  int i;
  ll ret = 1;
  for (i = 0; i < n; i++) {
    ret = ret * (i + 1);
    if (ret >= p)
      ret %= p;
  }
  return ret;
}

ll perm(ll n, ll k, ll p = MOD) {
  if (n < 0 || k < 0 || n < k)
    return 0;
  int i;
  ll ret = 1;
  for (i = 0; i < k; i++) {
    ret = ret * (n - i);
    if (ret >= p)
      ret %= p;
  }
  return ret;
}

ll binom(ll n, ll k, ll p = MOD) {
  if (n < 0 || k < 0 || n < k)
    return 0;
  int i;
  ll ret = 1, fact = 1;
  for (i = 0; i < k; i++) {
    ret = ret * (n - i);
    fact *= i + 1;
    if (ret >= p)
      ret %= p;
    if (fact >= p)
      fact %= p;
  }
  return (ret * modInv(fact)) % p;
}

void pushHeap(vector<int> &h, int n) {
  int i = h.size();
  h.push_back(n);
  while (i != 0 && h[(i - 1) / 2] < h[i]) {
    swap(h[i], h[(i - 1) / 2]);
    i = (i - 1) / 2;
  }
  h[i] = n;
}

int popHeap(vector<int> &h) {
  int n = h.size() - 1;
  if (n == -1)
    return 0;
  int i, ret = h[0];
  swap(h[0], h[n]);
  h.pop_back();
  for (i = 0; i < n;) {
    int j = 2 * i + 1;
    if (j >= n)
      break;
    if (j != n - 1 && h[j] < h[j + 1])
      j++;
    if (h[i] < h[j]) {
      swap(h[i], h[j]);
    }
    i = j;
  }
  return ret;
}

int num = 1;
int h, w;
vector<ll> sc, sd;
int c[400][400], ver[400][400];
void dfs(int x, int y, int color) {
  ver[x][y] = num;
  if (c[x][y] == 0)
    sc[num]++;
  else
    sd[num]++;
  for (int i = 0; i < 4; i++) {
    int p = x + dx[i];
    int q = y + dy[i];
    if (p < 0 || h <= p || q < 0 || w <= q)
      continue;
    if (ver[p][q] != 0)
      continue;
    if (c[p][q] == color)
      continue;
    dfs(p, q, c[p][q]);
  }
}

int main() {
  int i, j, k, cnt = 0;
  cin >> h >> w;
  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++) {
      char a;
      cin >> a;
      if (a == '.')
        c[i][j] = 0;
      else
        c[i][j] = 1;
    }
  }
  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++)
      ver[i][j] = 0;
  }
  sc.assign(h * w, 0);
  sd.assign(h * w, 0);
  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++) {
      if (ver[i][j] != 0)
        continue;
      dfs(i, j, c[i][j]);
      num++;
    }
  }
  ll ans = 0;
  for (i = 0; i < num; i++) {
    ans += sc[i] * sd[i];
  }
  cout << ans << endl;
}

Fixed submission:
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
using plll = pair<ll, pll>;
using graph = vector<vector<int>>;

const ll MOD = 1000000007;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

ll abs1(ll a) {
  if (a >= 0)
    return a;
  else
    return -a;
}

ll pow1(ll a, ll b, ll p = LLONG_MAX) {
  ll ret = 1;
  while (b != 0) {
    if ((b & 1) == 1) {
      ret *= a;
    }
    a *= a;
    if (a >= p)
      a %= p;
    b = b >> 1;
  }
  return ret;
}

int digit(ll a, ll b) {
  int i = 0;
  while (a != 0) {
    a /= b;
    i++;
  }
  return i;
}

ll gcd1(ll a, ll b) {
  if (a == 0 && b == 0)
    return 0;
  ll n;
  while (a % b != 0) {
    n = a % b;
    a = b;
    b = n;
  }
  return b;
}

ll solveLinear(ll n, ll m, ll c) {
  if (n == 0 && m == 0)
    return 0;
  ll a[100], b[100];
  a[0] = n;
  b[0] = m;
  int i = 1;
  while (b[i - 1] != 0) {
    a[i] = b[i - 1];
    b[i] = a[i - 1] % b[i - 1];
    i++;
  }
  n = i;
  if (c % a[n - 1] != 0) {
    return 0;
  }
  ll x = c / a[n - 1], y = 0;
  for (i = 1; i < n; i++) {
    ll cnt = x;
    x = y;
    y = cnt - (a[n - i - 1] / b[n - i - 1]) * y;
  }
  return x;
}

ll modInv(ll a, ll p = MOD) {
  a %= p;
  ll n = solveLinear(a, p, 1);
  n %= p;
  if (n < 0)
    return n + p;
  return n;
}

ll fact(ll n, ll p = MOD) {
  if (n < 0)
    return 0;
  int i;
  ll ret = 1;
  for (i = 0; i < n; i++) {
    ret = ret * (i + 1);
    if (ret >= p)
      ret %= p;
  }
  return ret;
}

ll perm(ll n, ll k, ll p = MOD) {
  if (n < 0 || k < 0 || n < k)
    return 0;
  int i;
  ll ret = 1;
  for (i = 0; i < k; i++) {
    ret = ret * (n - i);
    if (ret >= p)
      ret %= p;
  }
  return ret;
}

ll binom(ll n, ll k, ll p = MOD) {
  if (n < 0 || k < 0 || n < k)
    return 0;
  int i;
  ll ret = 1, fact = 1;
  for (i = 0; i < k; i++) {
    ret = ret * (n - i);
    fact *= i + 1;
    if (ret >= p)
      ret %= p;
    if (fact >= p)
      fact %= p;
  }
  return (ret * modInv(fact)) % p;
}

void pushHeap(vector<int> &h, int n) {
  int i = h.size();
  h.push_back(n);
  while (i != 0 && h[(i - 1) / 2] < h[i]) {
    swap(h[i], h[(i - 1) / 2]);
    i = (i - 1) / 2;
  }
  h[i] = n;
}

int popHeap(vector<int> &h) {
  int n = h.size() - 1;
  if (n == -1)
    return 0;
  int i, ret = h[0];
  swap(h[0], h[n]);
  h.pop_back();
  for (i = 0; i < n;) {
    int j = 2 * i + 1;
    if (j >= n)
      break;
    if (j != n - 1 && h[j] < h[j + 1])
      j++;
    if (h[i] < h[j]) {
      swap(h[i], h[j]);
    }
    i = j;
  }
  return ret;
}

int num = 1;
int h, w;
vector<ll> sc, sd;
int c[400][400], ver[400][400];
void dfs(int x, int y, int color) {
  ver[x][y] = num;
  if (c[x][y] == 0)
    sc[num]++;
  else
    sd[num]++;
  for (int i = 0; i < 4; i++) {
    int p = x + dx[i];
    int q = y + dy[i];
    if (p < 0 || h <= p || q < 0 || w <= q)
      continue;
    if (ver[p][q] != 0)
      continue;
    if (c[p][q] == color)
      continue;
    dfs(p, q, c[p][q]);
  }
}

int main() {
  int i, j, k, cnt = 0;
  cin >> h >> w;
  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++) {
      char a;
      cin >> a;
      if (a == '.')
        c[i][j] = 0;
      else
        c[i][j] = 1;
    }
  }
  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++)
      ver[i][j] = 0;
  }
  sc.assign(2 * h * w, 0);
  sd.assign(2 * h * w, 0);
  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++) {
      if (ver[i][j] != 0)
        continue;
      dfs(i, j, c[i][j]);
      num++;
    }
  }
  ll ans = 0;
  for (i = 0; i < num; i++) {
    ans += sc[i] * sd[i];
  }
  cout << ans << endl;
}