Problem p02609 (C++) — buggy submission, verdict: Runtime Error

// Optional FAST

// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC
// target("sse,sse2,sse3,ssse3,sse4,popcnt,fma,abm,mmx,avx,avx2,tune=native")

// Required Libraries

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/tree_policy.hpp>

// Required namespaces

using namespace std;
using namespace __gnu_pbds;

// Required defines

#define endl '\\n'

#define READ(X) cin >> X;
#define READV(X)                                                               \\
  long long X;                                                                 \\
  cin >> X;
#define READAR(A, N)                                                           \\
  long long A[N];                                                              \\
  for (long long i = 0; i < N; i++) {                                          \\
    cin >> A[i];                                                               \\
  }
#define rz(A, N) A.resize(N);
#define sz(X) (long long)(X.size())
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define FORI(a, b, c) for (long long a = b; a < c; a++)
#define FORD(a, b, c) for (long long a = b; a > c; a--)

// Required typedefs

typedef tree<long long, null_type, less<long long>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set;
typedef tree<long long, null_type, greater<long long>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set1;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;

// Required Constants

const long long inf = (long long)1e18;
long long MOD = (long long)(1e9 + 7);
const long long INIT = (long long)(1e6 + 1);
const long double PI = 3.14159265358979;

// Required random number generators

// mt19937 gen_rand_int(chrono::steady_clock::now().time_since_epoch().count());
// mt19937_64
// gen_rand_ll(chrono::steady_clock::now().time_since_epoch().count());

// Required Functions

ll power(ll x, ll y) {
  if (y == 0)
    return 1;
  ll p = power(x, y / 2) % MOD;
  p = (p * p) % MOD;

  return (y % 2 == 0) ? p : (x * p) % MOD;
}
ll modInverse(ll a) { return power(a, MOD - 2); }

// Work

int main() {
#ifndef ONLINE_JUDGE
  if (fopen("INPUT.txt", "r")) {
    freopen("INPUT.txt", "r", stdin);
    // freopen ("OUTPUT.txt" , "w" , stdout);
  }
#endif
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);

  clock_t clk;
  clk = clock();
  //-----------------------------------------------------------------------------------------------------------//

  READV(N);
  bool A[N];
  MOD = 0;
  FORI(i, 0, N) {
    char x;
    cin >> x;
    if (x == '0') {
      A[i] = false;
    } else {
      A[i] = true;
      MOD++;
    }
  }
  reverse(A, A + N);
  ll val[2] = {0};
  ll old_MOD = MOD;
  MOD++;
  FORI(i, 0, N) {
    val[1] += A[i] * power(2, i);
    val[1] %= MOD;
  }
  MOD--;
  if (MOD > 1) {
    MOD--;
    FORI(i, 0, N) {
      val[0] += A[i] * power(2, i);
      val[0] %= MOD;
    }
    MOD++;
  }
  FORD(i, N - 1, -1) {
    if (A[i]) {
      MOD--;
      if (MOD == 0) {
        cout << 0 << endl;
        continue;
      }
      ll z = (val[0] - power(2, i) + MOD) % MOD;
      ll cnt = 1;
      while (z > 0) {
        cnt++;
        MOD = 0;
        ll z1 = z;
        while (z1 > 0) {
          MOD += (z1 % 2);
          z1 = z1 / 2;
        }
        z = z % MOD;
      }
      cout << cnt << endl;
      MOD = old_MOD;
    } else {
      MOD++;
      if (MOD == 0) {
        cout << 0 << endl;
      }
      ll z = (val[1] + power(2, i)) % MOD;
      ll cnt = 1;
      while (z > 0) {
        cnt++;
        MOD = 0;
        ll z1 = z;
        while (z1 > 0) {
          MOD += (z1 % 2);
          z1 = z1 / 2;
        }
        z = z % MOD;
      }
      cout << cnt << endl;
      MOD = old_MOD;
    }
  }

  //-----------------------------------------------------------------------------------------------------------//

  clk = clock() - clk;
  cerr << fixed << setprecision(6) << "Time: " << ((double)clk) / CLOCKS_PER_SEC
       << endl;

  return 0;
}

Error: 0
Time: 0.000043


Fixed submission:

// Optional FAST

// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC
// target("sse,sse2,sse3,ssse3,sse4,popcnt,fma,abm,mmx,avx,avx2,tune=native")

// Required Libraries

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/tree_policy.hpp>

// Required namespaces

using namespace std;
using namespace __gnu_pbds;

// Required defines

#define endl '\\n'

#define READ(X) cin >> X;
#define READV(X)                                                               \\
  long long X;                                                                 \\
  cin >> X;
#define READAR(A, N)                                                           \\
  long long A[N];                                                              \\
  for (long long i = 0; i < N; i++) {                                          \\
    cin >> A[i];                                                               \\
  }
#define rz(A, N) A.resize(N);
#define sz(X) (long long)(X.size())
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define FORI(a, b, c) for (long long a = b; a < c; a++)
#define FORD(a, b, c) for (long long a = b; a > c; a--)

// Required typedefs

typedef tree<long long, null_type, less<long long>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set;
typedef tree<long long, null_type, greater<long long>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set1;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;

// Required Constants

const long long inf = (long long)1e18;
long long MOD = (long long)(1e9 + 7);
const long long INIT = (long long)(1e6 + 1);
const long double PI = 3.14159265358979;

// Required random number generators

// mt19937 gen_rand_int(chrono::steady_clock::now().time_since_epoch().count());
// mt19937_64
// gen_rand_ll(chrono::steady_clock::now().time_since_epoch().count());

// Required Functions

ll power(ll x, ll y) {
  if (y == 0)
    return 1;
  ll p = power(x, y / 2) % MOD;
  p = (p * p) % MOD;

  return (y % 2 == 0) ? p : (x * p) % MOD;
}
ll modInverse(ll a) { return power(a, MOD - 2); }

// Work

int main() {
#ifndef ONLINE_JUDGE
  if (fopen("INPUT.txt", "r")) {
    freopen("INPUT.txt", "r", stdin);
    // freopen ("OUTPUT.txt" , "w" , stdout);
  }
#endif
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);

  clock_t clk;
  clk = clock();
  //-----------------------------------------------------------------------------------------------------------//

  READV(N);
  bool A[N];
  MOD = 0;
  FORI(i, 0, N) {
    char x;
    cin >> x;
    if (x == '0') {
      A[i] = false;
    } else {
      A[i] = true;
      MOD++;
    }
  }
  reverse(A, A + N);
  ll val[2] = {0};
  ll old_MOD = MOD;
  MOD++;
  FORI(i, 0, N) {
    val[1] += A[i] * power(2, i);
    val[1] %= MOD;
  }
  MOD--;
  if (MOD >= 1) {
    MOD--;
    FORI(i, 0, N) {
      val[0] += A[i] * power(2, i);
      val[0] %= MOD;
    }
    MOD++;
  }
  FORD(i, N - 1, -1) {
    if (A[i]) {
      MOD--;
      if (MOD == 0) {
        cout << 0 << endl;
      }
      ll z = (val[0] - power(2, i) + MOD) % MOD;
      ll cnt = 1;
      while (z > 0) {
        cnt++;
        MOD = 0;
        ll z1 = z;
        while (z1 > 0) {
          MOD += (z1 % 2);
          z1 = z1 / 2;
        }
        z = z % MOD;
      }
      cout << cnt << endl;
      MOD = old_MOD;
    } else {
      MOD++;
      if (MOD == 0) {
        cout << 0 << endl;
      }
      ll z = (val[1] + power(2, i)) % MOD;
      ll cnt = 1;
      while (z > 0) {
        cnt++;
        MOD = 0;
        ll z1 = z;
        while (z1 > 0) {
          MOD += (z1 % 2);
          z1 = z1 / 2;
        }
        z = z % MOD;
      }
      cout << cnt << endl;
      MOD = old_MOD;
    }
  }

  //-----------------------------------------------------------------------------------------------------------//

  clk = clock() - clk;
  cerr << fixed << setprecision(6) << "Time: " << ((double)clk) / CLOCKS_PER_SEC
       << endl;

  return 0;
}