Problem p02685 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cmath>
#include <complex>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) for (ll i = ll(a); i < ll(b); ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, )(__VA_ARGS__)
#define all(x) (x).begin(), (x).end()
#define PRINT(V) cout << V << "\\n"
#define SORT(V) sort((V).begin(), (V).end())
#define RSORT(V) sort((V).rbegin(), (V).rend())
using namespace std;
using ll = long long;
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
inline void Yes(bool condition) {
  if (condition)
    PRINT("Yes");
  else
    PRINT("No");
}
template <class itr> void cins(itr first, itr last) {
  for (auto i = first; i != last; i++) {
    cin >> (*i);
  }
}
template <class itr> void array_output(itr start, itr goal) {
  string ans = "", k = " ";
  for (auto i = start; i != goal; i++)
    ans += to_string(*i) + k;
  if (!ans.empty())
    ans.pop_back();
  PRINT(ans);
}
ll gcd(ll a, ll b) { return a ? gcd(b % a, a) : b; }
const ll INF = 1e15;
const ll MOD = 100000000;
const ll MOD2 = 998244353;
typedef pair<ll, ll> P;
const ll MAX = 200010;
constexpr ll nx[8] = {1, 0, -1, 0, -1, -1, 1, 1};
constexpr ll ny[8] = {0, 1, 0, -1, -1, 1, -1, 1};
ll fac[MAX], finv[MAX], inv[MAX];
void COMinit() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (ll i = 2; i < MAX; i++) {
    fac[i] = fac[i - 1] * i % MOD2;
    inv[i] = MOD2 - inv[MOD2 % i] * (MOD2 / i) % MOD2;
    finv[i] = finv[i - 1] * inv[i] % MOD2;
  }
}

ll COM(ll n, ll k) {
  if (n < k)
    return 0;
  if (n < 0 || k < 0)
    return 0;
  return fac[n] * (finv[k] * finv[n - k] % MOD2) % MOD2;
}
ll RepeatSquaring(ll N, ll P, ll M) {
  if (P == 0)
    return 1;
  if (P % 2 == 0) {
    ll t = RepeatSquaring(N, P / 2, M);
    return t * t % M;
  }
  return N * RepeatSquaring(N, P - 1, M) % M;
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll n, m, k;
  cin >> n >> m >> k;
  ll ans = 0;
  COMinit();
  rep(i, k + 1) {
    ans += m * COM(n - 1, i) % MOD2 * RepeatSquaring(m - 1, n - i - 1, MOD2);
    ans %= MOD2;
  }
  PRINT(ans);
}


Error: WA

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cmath>
#include <complex>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) for (ll i = ll(a); i < ll(b); ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, )(__VA_ARGS__)
#define all(x) (x).begin(), (x).end()
#define PRINT(V) cout << V << "\\n"
#define SORT(V) sort((V).begin(), (V).end())
#define RSORT(V) sort((V).rbegin(), (V).rend())
using namespace std;
using ll = long long;
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
inline void Yes(bool condition) {
  if (condition)
    PRINT("Yes");
  else
    PRINT("No");
}
template <class itr> void cins(itr first, itr last) {
  for (auto i = first; i != last; i++) {
    cin >> (*i);
  }
}
template <class itr> void array_output(itr start, itr goal) {
  string ans = "", k = " ";
  for (auto i = start; i != goal; i++)
    ans += to_string(*i) + k;
  if (!ans.empty())
    ans.pop_back();
  PRINT(ans);
}
ll gcd(ll a, ll b) { return a ? gcd(b % a, a) : b; }
const ll INF = 1e15;
const ll MOD = 100000000;
const ll MOD2 = 998244353;
typedef pair<ll, ll> P;
const ll MAX = 200010;
constexpr ll nx[8] = {1, 0, -1, 0, -1, -1, 1, 1};
constexpr ll ny[8] = {0, 1, 0, -1, -1, 1, -1, 1};
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll n, k;
  cin >> n >> k;
  vector<ll> a(n);
  cins(all(a));
  rep(i, n) a[i]--;
  vector<bool> t(n, 0);
  ll index, now = 0, c = 0;
  while (true) {
    if (t[now]) {
      index = now;
      break;
    }
    c++;
    t[now] = 1;
    now = a[now];
  }
  ll cnt = 0;
  now = 0;
  while (now != index) {
    now = a[now];
    cnt++;
  }
  c -= cnt;
  ll ans = 0;
  cout << cnt << " " << c << endl;
  if (k <= cnt) {
    rep(i, k) { ans = a[ans]; }
    PRINT(ans + 1);
  } else {
    k -= cnt;
    k %= c;
    rep(i, k) { index = a[index]; }
    PRINT(index + 1);
  }
}