Problem p03718 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;

#define ms(s, n) memset(s, n, sizeof(s))
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define FORd(i, a, b) for (int i = (a)-1; i >= (b); i--)
#define FORall(it, a)                                                          \
  for (__typeof((a).begin()) it = (a).begin(); it != (a).end(); it++)
#define sz(a) int((a).size())
#define present(t, x) (t.find(x) != t.end())
#define all(a) (a).begin(), (a).end()
#define uni(a) (a).erase(unique(all(a)), (a).end())
#define pb push_back
#define pf push_front
#define mp make_pair
#define fi first
#define se second
#define prec(n) fixed << setprecision(n)
#define bit(n, i) (((n) >> (i)) & 1)
#define bitcount(n) __builtin_popcountll(n)
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pi;
typedef vector<int> vi;
typedef vector<pi> vii;
const int MOD = (int)1e9 + 7;
const int INF = (int)1e9;
const ll LINF = (ll)1e18;
const ld PI = acos((ld)-1);
const ld EPS = 1e-9;
inline ll gcd(ll a, ll b) {
  ll r;
  while (b) {
    r = a % b;
    a = b;
    b = r;
  }
  return a;
}
inline ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
inline ll fpow(ll n, ll k, int p = MOD) {
  ll r = 1;
  for (; k; k >>= 1) {
    if (k & 1)
      r = r * n % p;
    n = n * n % p;
  }
  return r;
}
template <class T> inline int chkmin(T &a, const T &val) {
  return val < a ? a = val, 1 : 0;
}
template <class T> inline int chkmax(T &a, const T &val) {
  return a < val ? a = val, 1 : 0;
}
inline ll isqrt(ll k) {
  ll r = sqrt(k) + 1;
  while (r * r > k)
    r--;
  return r;
}
inline ll icbrt(ll k) {
  ll r = cbrt(k) + 1;
  while (r * r * r > k)
    r--;
  return r;
}
inline void addmod(int &a, int val, int p = MOD) {
  if ((a = (a + val)) >= p)
    a -= p;
}
inline void submod(int &a, int val, int p = MOD) {
  if ((a = (a - val)) < 0)
    a += p;
}
inline int mult(int a, int b, int p = MOD) { return (ll)a * b % p; }
inline int inv(int a, int p = MOD) { return fpow(a, p - 2, p); }
inline int sign(ld x) { return x < -EPS ? -1 : x > +EPS; }
inline int sign(ld x, ld y) { return sign(x - y); }
#define db(x) cerr << #x << " = " << (x) << ", ";
#define endln cerr << "\n";
#define chkpt cerr << "-----\n";

template <class T, T oo> struct Dinic {
  static const int MAXV = 1e5 + 5;
  static const int MAXE = 1e6 + 5;
  int n, s, t, E;
  int adj[MAXE], nxt[MAXE], lst[MAXV], ptr[MAXV], lev[MAXV], que[MAXV];
  T flw[MAXE], cap[MAXE];
  void init(int n, int s, int t) {
    this->n = n, this->s = s, this->t = t, E = 0;
    fill_n(lst, n, -1);
  }
  void add(int u, int v, T c1, T c2) {
    adj[E] = v, flw[E] = 0, cap[E] = c1, nxt[E] = lst[u], lst[u] = E++;
    adj[E] = u, flw[E] = 0, cap[E] = c2, nxt[E] = lst[v], lst[v] = E++;
  }
  int bfs() {
    fill_n(lev, n, -1), lev[s] = 0;
    int qsize = 0;
    que[qsize++] = s;
    for (int i = 0; i < qsize; i++) {
      for (int u = que[i], e = lst[u]; ~e; e = nxt[e]) {
        int v = adj[e];
        if (flw[e] < cap[e] && !~lev[v]) {
          lev[v] = lev[u] + 1;
          que[qsize++] = v;
        }
      }
    }
    return lev[t] != -1;
  }
  T dfs(int u, T bot) {
    if (u == t)
      return bot;
    for (int &e = ptr[u]; ~e; e = nxt[e]) {
      int v = adj[e];
      T delta = 0;
      if (lev[v] == lev[u] + 1 && flw[e] < cap[e] &&
          (delta = dfs(v, min(bot, cap[e] - flw[e]))) > 0) {
        flw[e] += delta;
        flw[e ^ 1] -= delta;
        return delta;
      }
    }
    return 0;
  }
  T maxflow() {
    T total = 0;
    while (bfs()) {
      for (int i = 0; i < n; i++)
        ptr[i] = lst[i];
      for (T delta = dfs(s, oo); delta > 0; delta = dfs(s, oo))
        total += delta;
    }
    return total;
  }
};
Dinic<int, (int)1e9> dinic;

const int maxn = 100 + 5;
int n, m;
int a[maxn][maxn];

inline int id1(int i, int j) { return (i * m + j) * 2; }

inline int id2(int i, int j) { return (i * m + j) * 2 + 1; }

void solve() {
  cin >> n >> m;
  FOR(i, 0, n) {
    string s;
    cin >> s;
    FOR(j, 0, m) a[i][j] = s[j];
  }
  int s, t;
  FOR(i, 0, n) FOR(j, 0, m) {
    if (a[i][j] == 'S') {
      s = id1(i, j);
    }
    if (a[i][j] == 'T') {
      t = id2(i, j);
    }
  }
  dinic.init(n * m * 2, s, t);
  FOR(i, 0, n) FOR(j, 0, m) if (a[i][j] != '.') {
    FOR(k, 0, m) if (k != j && a[i][k] != '.') {
      dinic.add(id2(i, j), id1(i, k), INF, 0);
    }
    FOR(k, 0, n) if (k != i && a[k][j] != '.') {
      dinic.add(id2(i, j), id1(k, j), INF, 0);
    }
    if (id1(i, j) != s && id2(i, j) != t) {
      dinic.add(id1(i, j), id2(i, j), 1, 0);
    } else {
      dinic.add(id1(i, j), id2(i, j), INF, 0);
    }
  }
  int ans = dinic.maxflow();
  if (ans == INF)
    ans = -1;
  cout << ans << "\n";
}

int main() {
  int JUDGE_ONLINE = 1;
  if (fopen("in.txt", "r")) {
    JUDGE_ONLINE = 0;
    assert(freopen("in.txt", "r", stdin));
    // assert(freopen("out.txt", "w", stdout));
  } else {
    ios_base::sync_with_stdio(0), cin.tie(0);
  }
  solve();
  if (!JUDGE_ONLINE) {
    // cout << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
  }
  return 0;
}

Fixed submission:
#include <bits/stdc++.h>
using namespace std;

#define ms(s, n) memset(s, n, sizeof(s))
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define FORd(i, a, b) for (int i = (a)-1; i >= (b); i--)
#define FORall(it, a)                                                          \
  for (__typeof((a).begin()) it = (a).begin(); it != (a).end(); it++)
#define sz(a) int((a).size())
#define present(t, x) (t.find(x) != t.end())
#define all(a) (a).begin(), (a).end()
#define uni(a) (a).erase(unique(all(a)), (a).end())
#define pb push_back
#define pf push_front
#define mp make_pair
#define fi first
#define se second
#define prec(n) fixed << setprecision(n)
#define bit(n, i) (((n) >> (i)) & 1)
#define bitcount(n) __builtin_popcountll(n)
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pi;
typedef vector<int> vi;
typedef vector<pi> vii;
const int MOD = (int)1e9 + 7;
const int INF = (int)1e9;
const ll LINF = (ll)1e18;
const ld PI = acos((ld)-1);
const ld EPS = 1e-9;
inline ll gcd(ll a, ll b) {
  ll r;
  while (b) {
    r = a % b;
    a = b;
    b = r;
  }
  return a;
}
inline ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
inline ll fpow(ll n, ll k, int p = MOD) {
  ll r = 1;
  for (; k; k >>= 1) {
    if (k & 1)
      r = r * n % p;
    n = n * n % p;
  }
  return r;
}
template <class T> inline int chkmin(T &a, const T &val) {
  return val < a ? a = val, 1 : 0;
}
template <class T> inline int chkmax(T &a, const T &val) {
  return a < val ? a = val, 1 : 0;
}
inline ll isqrt(ll k) {
  ll r = sqrt(k) + 1;
  while (r * r > k)
    r--;
  return r;
}
inline ll icbrt(ll k) {
  ll r = cbrt(k) + 1;
  while (r * r * r > k)
    r--;
  return r;
}
inline void addmod(int &a, int val, int p = MOD) {
  if ((a = (a + val)) >= p)
    a -= p;
}
inline void submod(int &a, int val, int p = MOD) {
  if ((a = (a - val)) < 0)
    a += p;
}
inline int mult(int a, int b, int p = MOD) { return (ll)a * b % p; }
inline int inv(int a, int p = MOD) { return fpow(a, p - 2, p); }
inline int sign(ld x) { return x < -EPS ? -1 : x > +EPS; }
inline int sign(ld x, ld y) { return sign(x - y); }
#define db(x) cerr << #x << " = " << (x) << ", ";
#define endln cerr << "\n";
#define chkpt cerr << "-----\n";

template <class T, T oo> struct Dinic {
  static const int MAXV = 1e6 + 5;
  static const int MAXE = 4.5e6 + 5;
  int n, s, t, E;
  int adj[MAXE], nxt[MAXE], lst[MAXV], ptr[MAXV], lev[MAXV], que[MAXV];
  T flw[MAXE], cap[MAXE];
  void init(int n, int s, int t) {
    this->n = n, this->s = s, this->t = t, E = 0;
    fill_n(lst, n, -1);
  }
  void add(int u, int v, T c1, T c2) {
    adj[E] = v, flw[E] = 0, cap[E] = c1, nxt[E] = lst[u], lst[u] = E++;
    adj[E] = u, flw[E] = 0, cap[E] = c2, nxt[E] = lst[v], lst[v] = E++;
  }
  int bfs() {
    fill_n(lev, n, -1), lev[s] = 0;
    int qsize = 0;
    que[qsize++] = s;
    for (int i = 0; i < qsize; i++) {
      for (int u = que[i], e = lst[u]; ~e; e = nxt[e]) {
        int v = adj[e];
        if (flw[e] < cap[e] && !~lev[v]) {
          lev[v] = lev[u] + 1;
          que[qsize++] = v;
        }
      }
    }
    return lev[t] != -1;
  }
  T dfs(int u, T bot) {
    if (u == t)
      return bot;
    for (int &e = ptr[u]; ~e; e = nxt[e]) {
      int v = adj[e];
      T delta = 0;
      if (lev[v] == lev[u] + 1 && flw[e] < cap[e] &&
          (delta = dfs(v, min(bot, cap[e] - flw[e]))) > 0) {
        flw[e] += delta;
        flw[e ^ 1] -= delta;
        return delta;
      }
    }
    return 0;
  }
  T maxflow() {
    T total = 0;
    while (bfs()) {
      for (int i = 0; i < n; i++)
        ptr[i] = lst[i];
      for (T delta = dfs(s, oo); delta > 0; delta = dfs(s, oo))
        total += delta;
    }
    return total;
  }
};
Dinic<int, (int)1e9> dinic;

const int maxn = 100 + 5;
int n, m;
int a[maxn][maxn];

inline int id1(int i, int j) { return (i * m + j) * 2; }

inline int id2(int i, int j) { return (i * m + j) * 2 + 1; }

void solve() {
  cin >> n >> m;
  FOR(i, 0, n) {
    string s;
    cin >> s;
    FOR(j, 0, m) a[i][j] = s[j];
  }
  int s, t;
  FOR(i, 0, n) FOR(j, 0, m) {
    if (a[i][j] == 'S') {
      s = id1(i, j);
    }
    if (a[i][j] == 'T') {
      t = id2(i, j);
    }
  }
  dinic.init(n * m * 2, s, t);
  FOR(i, 0, n) FOR(j, 0, m) if (a[i][j] != '.') {
    FOR(k, 0, m) if (k != j && a[i][k] != '.') {
      dinic.add(id2(i, j), id1(i, k), INF, 0);
    }
    FOR(k, 0, n) if (k != i && a[k][j] != '.') {
      dinic.add(id2(i, j), id1(k, j), INF, 0);
    }
    if (id1(i, j) != s && id2(i, j) != t) {
      dinic.add(id1(i, j), id2(i, j), 1, 0);
    } else {
      dinic.add(id1(i, j), id2(i, j), INF, 0);
    }
  }
  int ans = dinic.maxflow();
  if (ans == INF)
    ans = -1;
  cout << ans << "\n";
}

int main() {
  int JUDGE_ONLINE = 1;
  if (fopen("in.txt", "r")) {
    JUDGE_ONLINE = 0;
    assert(freopen("in.txt", "r", stdin));
    // assert(freopen("out.txt", "w", stdout));
  } else {
    ios_base::sync_with_stdio(0), cin.tie(0);
  }
  solve();
  if (!JUDGE_ONLINE) {
    // cout << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
  }
  return 0;
}