Problem p02962 (C++)

Buggy submission (status: Runtime Error):
#include <algorithm>
#include <bitset>
#include <complex>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <istream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<ll> vec;
typedef vector<vec> mat;
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define revrep(i, n) for (ll i = (n - 1); i >= 0; i--)
#define pb push_back
#define f first
#define s second
ll max(ll a, ll b) { return (a > b) ? a : b; }
ll min(ll a, ll b) { return (a < b) ? a : b; }
ll max3(ll a, ll b, ll c) { return max(a, max(b, c)); };
ll min3(ll a, ll b, ll c) { return min(a, min(b, c)); };
ll max4(ll a, ll b, ll c, ll d) { return max(max(a, b), min(c, d)); };
ll min4(ll a, ll b, ll c, ll d) { return min(min(a, b), min(c, d)); };
ll max5(ll a, ll b, ll c, ll d, ll e) { return max(max(a, b), max3(c, d, e)); };
ll min5(ll a, ll b, ll c, ll d, ll e) { return min(min(a, b), min3(c, d, e)); };

const ll INFL = 1LL << 60; // 10^18 = 2^60
const int INF = 1 << 30;   // 10^9
ll MOD = 1000000007;
// ll MOD = 998244353;
vector<ll> dy = {0, 0, 1, -1, 1, 1, -1, -1, 0};
vector<ll> dx = {1, -1, 0, 0, 1, -1, 1, -1, 0};

ll pow_long(ll x, ll k) {
  ll res = 1;
  while (k > 0) {
    if (k % 2)
      res *= x;
    x *= x;
    k /= 2;
  }
  return res;
}
ll pow_mod(ll x, ll k) {
  x %= MOD;
  x += MOD;
  x %= MOD;
  ll res = 1;
  while (k > 0) {
    if (k % 2) {
      res *= x;
      res %= MOD;
    }
    x *= x;
    x %= MOD;
    k /= 2;
  }
  return res;
}

ll inverse(ll x) { return pow_mod(x, MOD - 2); };

ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}

ll lcm(ll x, ll y) { return x / gcd(x, y) * y; };

ll kai_mod(ll x) {
  if (x == 0)
    return 1;
  return x * kai_mod(x - 1) % MOD;
}

/*
//コンビネーション
const int MAXcomb = 200010;
ll fac[MAXcomb], finv[MAXcomb], inv[MAXcomb];
//facはn!,finvは1/n!
//invは逆元
void COMinit(){
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for(int i = 2; i < MAXcomb; i++){
        fac[i] = fac[i-1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD/i) % MOD;
        finv[i] = finv[i-1] * inv[i] % MOD;
    }
}
ll comb(int n, int k){
    if(n < k) return 0;
    if(n < 0 || k < 0) return 0;
    return fac[n] * finv[k] % MOD * finv[n-k] % MOD;
}
*/

string S, T;
vector<bool> canStart;
const ll MAX_V = 200010;

ll par[MAX_V]; //
ll Rank[MAX_V];
ll child[MAX_V];

void init_UF() {
  for (ll i = 0; i < MAX_V; i++) {
    par[i] = i;
    Rank[i] = 1;
    if (canStart[i])
      child[i] = 1;
  }
}

ll find(ll x) {
  if (par[x] == x)
    return x;
  else {
    return par[x] = find(par[x]);
  }
}

bool same(ll x, ll y) { return find(x) == find(y); }

void unite(ll x, ll y) {
  ll rx = find(x), ry = find(y);
  if (rx != ry) {
    if (Rank[rx] >= Rank[ry]) {
      par[ry] = rx;
      if (Rank[rx] == Rank[ry])
        Rank[rx]++;
      child[rx] += child[ry];
    } else {
      par[rx] = ry;
      child[ry] += child[rx];
    }
  }
}

int main() {
  cin >> S >> T;
  canStart.resize(S.size(), 0);
  ll a = 998244353;
  ll hashS = 0, hashT = 0;
  rep(i, T.size()) { hashS = (hashS * a + S[i % S.size()]) % MOD; }
  rep(i, T.size()) { hashT = (hashT * a + T[i]) % MOD; }
  ll po = pow_mod(a, T.size());
  rep(i, S.size()) {
    if (hashS == hashT)
      canStart[i] = 1;
    hashS =
        ((hashS * a + S[(i + T.size()) % S.size()] - S[i] * po) % MOD + MOD) %
        MOD;
  }
  init_UF();
  bool inf = 0;
  rep(i, S.size()) {
    ll to = (i + T.size()) % S.size();
    if (canStart[i] == 0 || canStart[to] == 0)
      continue;
    if (same(i, to))
      inf = 1;
    unite(i, to);
  }
  ll ans = 0;
  if (inf)
    cout << -1 << endl;
  else {
    rep(i, S.size()) { ans = max(ans, child[i]); }
    cout << ans << endl;
  }
}


Fixed submission:
#include <algorithm>
#include <bitset>
#include <complex>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <istream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<ll> vec;
typedef vector<vec> mat;
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define revrep(i, n) for (ll i = (n - 1); i >= 0; i--)
#define pb push_back
#define f first
#define s second
ll max(ll a, ll b) { return (a > b) ? a : b; }
ll min(ll a, ll b) { return (a < b) ? a : b; }
ll max3(ll a, ll b, ll c) { return max(a, max(b, c)); };
ll min3(ll a, ll b, ll c) { return min(a, min(b, c)); };
ll max4(ll a, ll b, ll c, ll d) { return max(max(a, b), min(c, d)); };
ll min4(ll a, ll b, ll c, ll d) { return min(min(a, b), min(c, d)); };
ll max5(ll a, ll b, ll c, ll d, ll e) { return max(max(a, b), max3(c, d, e)); };
ll min5(ll a, ll b, ll c, ll d, ll e) { return min(min(a, b), min3(c, d, e)); };

const ll INFL = 1LL << 60; // 10^18 = 2^60
const int INF = 1 << 30;   // 10^9
ll MOD = 1000000007;
// ll MOD = 998244353;
vector<ll> dy = {0, 0, 1, -1, 1, 1, -1, -1, 0};
vector<ll> dx = {1, -1, 0, 0, 1, -1, 1, -1, 0};

ll pow_long(ll x, ll k) {
  ll res = 1;
  while (k > 0) {
    if (k % 2)
      res *= x;
    x *= x;
    k /= 2;
  }
  return res;
}
ll pow_mod(ll x, ll k) {
  x %= MOD;
  x += MOD;
  x %= MOD;
  ll res = 1;
  while (k > 0) {
    if (k % 2) {
      res *= x;
      res %= MOD;
    }
    x *= x;
    x %= MOD;
    k /= 2;
  }
  return res;
}

ll inverse(ll x) { return pow_mod(x, MOD - 2); };

ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}

ll lcm(ll x, ll y) { return x / gcd(x, y) * y; };

ll kai_mod(ll x) {
  if (x == 0)
    return 1;
  return x * kai_mod(x - 1) % MOD;
}

/*
//コンビネーション
const int MAXcomb = 200010;
ll fac[MAXcomb], finv[MAXcomb], inv[MAXcomb];
//facはn!,finvは1/n!
//invは逆元
void COMinit(){
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for(int i = 2; i < MAXcomb; i++){
        fac[i] = fac[i-1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD/i) % MOD;
        finv[i] = finv[i-1] * inv[i] % MOD;
    }
}
ll comb(int n, int k){
    if(n < k) return 0;
    if(n < 0 || k < 0) return 0;
    return fac[n] * finv[k] % MOD * finv[n-k] % MOD;
}
*/

string S, T;
vector<bool> canStart;
const ll MAX_V = 1000010;

ll par[MAX_V]; //
ll Rank[MAX_V];
ll child[MAX_V];

void init_UF() {
  for (ll i = 0; i < MAX_V; i++) {
    par[i] = i;
    Rank[i] = 1;
    if (canStart[i])
      child[i] = 1;
  }
}

ll find(ll x) {
  if (par[x] == x)
    return x;
  else {
    return par[x] = find(par[x]);
  }
}

bool same(ll x, ll y) { return find(x) == find(y); }

void unite(ll x, ll y) {
  ll rx = find(x), ry = find(y);
  if (rx != ry) {
    if (Rank[rx] >= Rank[ry]) {
      par[ry] = rx;
      if (Rank[rx] == Rank[ry])
        Rank[rx]++;
      child[rx] += child[ry];
    } else {
      par[rx] = ry;
      child[ry] += child[rx];
    }
  }
}

int main() {
  cin >> S >> T;
  canStart.resize(S.size(), 0);
  ll a = 998244353;
  ll hashS = 0, hashT = 0;
  rep(i, T.size()) { hashS = (hashS * a + S[i % S.size()]) % MOD; }
  rep(i, T.size()) { hashT = (hashT * a + T[i]) % MOD; }
  ll po = pow_mod(a, T.size());
  rep(i, S.size()) {
    if (hashS == hashT)
      canStart[i] = 1;
    hashS =
        ((hashS * a + S[(i + T.size()) % S.size()] - S[i] * po) % MOD + MOD) %
        MOD;
  }
  init_UF();
  bool inf = 0;
  rep(i, S.size()) {
    ll to = (i + T.size()) % S.size();
    if (canStart[i] == 0 || canStart[to] == 0)
      continue;
    if (same(i, to))
      inf = 1;
    unite(i, to);
  }
  ll ans = 0;
  if (inf)
    cout << -1 << endl;
  else {
    rep(i, S.size()) { ans = max(ans, child[i]); }
    cout << ans << endl;
  }
}