Problem p02609 (C++)

Buggy submission (status: Runtime Error):
/*
   Created by Rahul Goel.
*/
/*******************************************************************************/
#include <algorithm>
#include <cmath>
#include <cstring>
#include <deque>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
/*******************************************************************************/
using namespace std;
using ll = long long;
using ld = long double;
const ll mod = 1000000007;
const int INF = 1e9;
const ll LINF = 1e18;
/*******************************************************************************/
/*
.-.. . -. -.- .- / .. ... / .-.. --- ...- . -.-.--
 */
/* For PBDS */
/*Two new methods X.order_of_key() and X.find_by_order()*/
/*
#include <bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,
tree_order_statistics_node_update>;
*/

/*******************************************************************************/
ll mod_sum() { return 0LL; }
template <typename T, typename... Args> T mod_sum(T a, Args... args) {
  return ((a + mod_sum(args...)) % mod + mod) % mod;
}

ll mod_prod() { return 1LL; }
template <typename T, typename... Args> T mod_prod(T a, Args... args) {
  return (a * mod_prod(args...)) % mod;
}
/*******************************************************************************/
using pii = pair<ll, ll>;
using vi = vector<ll>;
using vb = vector<bool>;
using vvi = vector<vector<ll>>;
using vvb = vector<vector<bool>>;
using vpii = vector<pii>;
using vvpii = vector<vector<pii>>;
#ifdef ONLINE_JUDGE
#define endl '\n'
#endif
#define fastio                                                                 \
  ios_base::sync_with_stdio(0);                                                \
  cin.tie(0);                                                                  \
  cout.tie(0)
#define all(c) (c).begin(), (c).end()
#define present(c, x) ((c).find(x) != (c).end())
#define cpresent(c, x) (find(all(c), x) != (c).end())
#define uniq(c) (c).resize(distance((c).begin(), unique(all(c))))
#define min_pq(t) priority_queue<t, vector<t>, greater<t>>
#define max_pq(t) priority_queue<t>
#define pb push_back
#define ff first
#define ss second
/*******************************************************************************/

/*
    Code begins after this.
*/

ll popcount(ll n) {
  ll cnt = 0;
  while (n)
    cnt += (n & 1), n >>= 1;
  return cnt;
}

ll f(ll n) {
  if (n == 0)
    return 0;
  return 1 + f(n % popcount(n));
}

ll power(ll x, ll y, ll m) {
  ll ret = 1;
  while (y) {
    if (y & 1)
      ret = (ret * x) % m;
    y >>= 1;
    x = (x * x) % m;
  }
  return ret;
}

ll solve() {
  ll n;
  cin >> n;
  string str;
  cin >> str;

  ll cnt1 = 0;
  for (char &x : str)
    cnt1 += (x == '1');

  ll val0 = 0, val1 = 0, val2 = 0;
  for (ll i = 0; i < n; i++) {
    if (str[i] == '1') {
      val0 = (val0 + power(2, n - i - 1, cnt1 - 1)) % (cnt1 - 1);
      val1 = (val1 + power(2, n - i - 1, cnt1 - 0)) % (cnt1 - 0);
      val2 = (val2 + power(2, n - i - 1, cnt1 + 1)) % (cnt1 + 1);
    }
  }

  vi ans;

  for (ll i = 0; i < n; i++) {
    if (str[i] == '1') {
      str[i] = '0';
      if (cnt1 - 1 == 0) {
        ans.pb(0);
        continue;
      }

      // cnt1 decreases by 1
      ll val =
          ((val0 - power(2, n - i - 1, cnt1 - 1)) % (cnt1 - 1) + cnt1 - 1) %
          (cnt1 - 1);
      ans.pb(1 + f(val));

      str[i] = '1';
    } else {
      str[i] = '1';
      if (cnt1 + 1 == 0) {
        ans.pb(0);
        continue;
      }

      // cnt1 increases by 1
      ll val = (val2 + power(2, n - i - 1, cnt1 + 1) + cnt1 + 1) % (cnt1 + 1);
      ans.pb(1 + f(val));

      str[i] = '0';
    }
  }

  for (ll x : ans)
    cout << x << endl;

  return 0;
}

signed main() {
  fastio;

  ll t = 1;
  while (t--)
    solve();

  return 0;
}

/*******************************************************************************/
// Remeber - In a custom comparator cmp(a, b) a==b must always return to false.


Fixed submission:
/*
   Created by Rahul Goel.
*/
/*******************************************************************************/
#include <algorithm>
#include <cmath>
#include <cstring>
#include <deque>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
/*******************************************************************************/
using namespace std;
using ll = long long;
using ld = long double;
const ll mod = 1000000007;
const int INF = 1e9;
const ll LINF = 1e18;
/*******************************************************************************/
/*
.-.. . -. -.- .- / .. ... / .-.. --- ...- . -.-.--
 */
/* For PBDS */
/*Two new methods X.order_of_key() and X.find_by_order()*/
/*
#include <bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,
tree_order_statistics_node_update>;
*/

/*******************************************************************************/
ll mod_sum() { return 0LL; }
template <typename T, typename... Args> T mod_sum(T a, Args... args) {
  return ((a + mod_sum(args...)) % mod + mod) % mod;
}

ll mod_prod() { return 1LL; }
template <typename T, typename... Args> T mod_prod(T a, Args... args) {
  return (a * mod_prod(args...)) % mod;
}
/*******************************************************************************/
using pii = pair<ll, ll>;
using vi = vector<ll>;
using vb = vector<bool>;
using vvi = vector<vector<ll>>;
using vvb = vector<vector<bool>>;
using vpii = vector<pii>;
using vvpii = vector<vector<pii>>;
#ifdef ONLINE_JUDGE
#define endl '\n'
#endif
#define fastio                                                                 \
  ios_base::sync_with_stdio(0);                                                \
  cin.tie(0);                                                                  \
  cout.tie(0)
#define all(c) (c).begin(), (c).end()
#define present(c, x) ((c).find(x) != (c).end())
#define cpresent(c, x) (find(all(c), x) != (c).end())
#define uniq(c) (c).resize(distance((c).begin(), unique(all(c))))
#define min_pq(t) priority_queue<t, vector<t>, greater<t>>
#define max_pq(t) priority_queue<t>
#define pb push_back
#define ff first
#define ss second
/*******************************************************************************/

/*
    Code begins after this.
*/

ll popcount(ll n) {
  ll cnt = 0;
  while (n)
    cnt += (n & 1), n >>= 1;
  return cnt;
}

ll f(ll n) {
  if (n == 0)
    return 0;
  return 1 + f(n % popcount(n));
}

ll power(ll x, ll y, ll m) {
  ll ret = 1;
  while (y) {
    if (y & 1)
      ret = (ret * x) % m;
    y >>= 1;
    x = (x * x) % m;
  }
  return ret;
}

ll solve() {
  ll n;
  cin >> n;
  string str;
  cin >> str;

  ll cnt1 = 0;
  for (char &x : str)
    cnt1 += (x == '1');

  ll val0 = 0, val1 = 0, val2 = 0;
  for (ll i = 0; i < n; i++) {
    if (str[i] == '1') {
      if (cnt1 - 1 > 0)
        val0 = (val0 + power(2, n - i - 1, cnt1 - 1)) % (cnt1 - 1);
      val1 = (val1 + power(2, n - i - 1, cnt1 - 0)) % (cnt1 - 0);
      val2 = (val2 + power(2, n - i - 1, cnt1 + 1)) % (cnt1 + 1);
    }
  }

  vi ans;

  for (ll i = 0; i < n; i++) {
    if (str[i] == '1') {
      str[i] = '0';
      if (cnt1 - 1 == 0) {
        ans.pb(0);
        continue;
      }

      // cnt1 decreases by 1
      ll val =
          ((val0 - power(2, n - i - 1, cnt1 - 1)) % (cnt1 - 1) + cnt1 - 1) %
          (cnt1 - 1);
      ans.pb(1 + f(val));

      str[i] = '1';
    } else {
      str[i] = '1';
      if (cnt1 + 1 == 0) {
        ans.pb(0);
        continue;
      }

      // cnt1 increases by 1
      ll val = (val2 + power(2, n - i - 1, cnt1 + 1) + cnt1 + 1) % (cnt1 + 1);
      ans.pb(1 + f(val));

      str[i] = '0';
    }
  }

  for (ll x : ans)
    cout << x << endl;

  return 0;
}

signed main() {
  fastio;

  ll t = 1;
  while (t--)
    solve();

  return 0;
}

/*******************************************************************************/
// Remeber - In a custom comparator cmp(a, b) a==b must always return to false.