Problem p03286 (C++)

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

typedef unsigned long ul;
typedef unsigned long long ull;
typedef long long ll;
typedef vector<ll> vint;
typedef vector<vector<ll>> vvint;
typedef vector<vector<vector<ll>>> vvvint;
typedef vector<string> vstring;
typedef vector<vector<string>> vvstring;
typedef vector<char> vchar;
typedef vector<vector<char>> vvchar;
typedef vector<long double> vdouble;
typedef vector<vector<long double>> vvdouble;
typedef vector<vector<vector<long double>>> vvvdouble;
typedef pair<ll, ll> pint;
typedef vector<pint> vpint;
typedef vector<bool> vbool;

#define rep(i, n) for (ll i = 0; i < n; i++)
#define repf(i, f, n) for (ll i = f; i < n; i++)
#define repr(i, n) for (ll i = n - 1; i >= 0; i--)
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define ALL(obj) (obj).begin(), (obj).end()
// #define LLONG_MAX 9223372036854775806
#define vmax(vec) *max_element(vec.begin(), vec.end())
#define vmin(vec) *min_element(vec.begin(), vec.end())
#define vsort(vec) sort(vec.begin(), vec.end())
#define vsortgr(vec) sort(vec.begin(), vec.end(), greater<ll>())
#define MOD 1000000007
// #define MOD 998244353
// #define MOD LLONG_MAX
const double PI = 3.14159265358979323846;
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;
}

int dy[] = {0, 0, 1, -1};
int dx[] = {
    1,
    -1,
    0,
    0,
};

void printv(vint &v) {
  for (auto e : v)
    cout << e << " ";
  cout << endl;
}

// 繰り返し二乗法
ll power(ll a, ll b) {
  if (a == 1)
    return a;
  // if(a==0)re
  ll res = 1;
  while (b > 0) {
    if (b & 1)
      res = res * a % MOD;
    a = a * a % MOD;
    b >>= 1;
  }
  return res;
}

const int MAX = 2100000;

ll fact[MAX], fact_inv[MAX];

void init_fact(ll n) {
  fact[0] = 1;
  // 階乗の計算
  for (ll i = 0; i < n; i++)
    fact[i + 1] = fact[i] * (i + 1) % MOD;
  fact_inv[n] = power(fact[n], MOD - 2);
  // 逆元の計算
  for (ll i = n - 1; i >= 0; i--)
    fact_inv[i] = fact_inv[i + 1] * (i + 1) % MOD;
}

ll comb(ll n, ll r) {
  return (fact[n] * fact_inv[r]) % MOD * fact_inv[n - r] % MOD;
}

ll perm(ll n, ll r) { return (fact[n] * fact_inv[n - r]) % MOD; }

int main() {
  cout << fixed << setprecision(10);

  ll n;
  cin >> n;
  vint ans;

  if (n == 0) {
    cout << 0 << endl;
    return 0;
  }

  ll cnt = 0;
  while (n != 0) {
    if (n % (2 << cnt) == 0) {
      ans.push_back(0);
    } else {
      ans.push_back(1);
      ll delta = 1ll << cnt;
      if (cnt % 2)
        delta *= -1;
      n -= delta;
    }
    cnt++;
  }
  reverse(ALL(ans));
  for (auto e : ans)
    cout << e;
  cout << endl;

  return 0;
}

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

typedef unsigned long ul;
typedef unsigned long long ull;
typedef long long ll;
typedef vector<ll> vint;
typedef vector<vector<ll>> vvint;
typedef vector<vector<vector<ll>>> vvvint;
typedef vector<string> vstring;
typedef vector<vector<string>> vvstring;
typedef vector<char> vchar;
typedef vector<vector<char>> vvchar;
typedef vector<long double> vdouble;
typedef vector<vector<long double>> vvdouble;
typedef vector<vector<vector<long double>>> vvvdouble;
typedef pair<ll, ll> pint;
typedef vector<pint> vpint;
typedef vector<bool> vbool;

#define rep(i, n) for (ll i = 0; i < n; i++)
#define repf(i, f, n) for (ll i = f; i < n; i++)
#define repr(i, n) for (ll i = n - 1; i >= 0; i--)
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define ALL(obj) (obj).begin(), (obj).end()
// #define LLONG_MAX 9223372036854775806
#define vmax(vec) *max_element(vec.begin(), vec.end())
#define vmin(vec) *min_element(vec.begin(), vec.end())
#define vsort(vec) sort(vec.begin(), vec.end())
#define vsortgr(vec) sort(vec.begin(), vec.end(), greater<ll>())
#define MOD 1000000007
// #define MOD 998244353
// #define MOD LLONG_MAX
const double PI = 3.14159265358979323846;
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;
}

int dy[] = {0, 0, 1, -1};
int dx[] = {
    1,
    -1,
    0,
    0,
};

void printv(vint &v) {
  for (auto e : v)
    cout << e << " ";
  cout << endl;
}

// 繰り返し二乗法
ll power(ll a, ll b) {
  if (a == 1)
    return a;
  // if(a==0)re
  ll res = 1;
  while (b > 0) {
    if (b & 1)
      res = res * a % MOD;
    a = a * a % MOD;
    b >>= 1;
  }
  return res;
}

const int MAX = 2100000;

ll fact[MAX], fact_inv[MAX];

void init_fact(ll n) {
  fact[0] = 1;
  // 階乗の計算
  for (ll i = 0; i < n; i++)
    fact[i + 1] = fact[i] * (i + 1) % MOD;
  fact_inv[n] = power(fact[n], MOD - 2);
  // 逆元の計算
  for (ll i = n - 1; i >= 0; i--)
    fact_inv[i] = fact_inv[i + 1] * (i + 1) % MOD;
}

ll comb(ll n, ll r) {
  return (fact[n] * fact_inv[r]) % MOD * fact_inv[n - r] % MOD;
}

ll perm(ll n, ll r) { return (fact[n] * fact_inv[n - r]) % MOD; }

int main() {
  cout << fixed << setprecision(10);

  ll n;
  cin >> n;
  vint ans;

  if (n == 0) {
    cout << 0 << endl;
    return 0;
  }

  ll cnt = 0;
  while (n != 0) {
    if (n % (2ll << cnt) == 0) {
      ans.push_back(0);
    } else {
      ans.push_back(1);
      ll delta = 1ll << cnt;
      if (cnt % 2)
        delta *= -1;
      n -= delta;
    }
    cnt++;
  }
  reverse(ALL(ans));
  for (auto e : ans)
    cout << e;
  cout << endl;

  return 0;
}