Problem p03849 (C++)

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

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define _USE_MATH_DEFINES_
#define ll long long
#define ld long double
#define Accepted 0
#define pb push_back
#define mp make_pair
#define sz(x) (int)(x.size())
#define every(x) x.begin(), x.end()
#define F first
#define S second
#define lb lower_bound
#define ub upper_bound
#define For(i, x, y) for (ll i = x; i <= y; i++)
#define FOr(i, x, y) for (ll i = x; i >= y; i--)
#define SpeedForce ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
// ROAD to... Red

inline void Input_Output() {
  // freopen(".in", "r", stdin);
  // freopen(".out", "w", stdout);
}

const double eps = 0.000001;
const ld pi = acos(-1);
const int maxn = 1e7 + 9;
const int mod = 1e9 + 7;
const ll MOD = 1e18 + 9;
const ll INF = 1e18 + 123;
const int inf = 2e9 + 11;
const int mxn = 1e6 + 9;
const int N = 5e5 + 123;
const int LIM = 52;
const int pri = 997;
const int Magic = 2101;

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

ll n;
ll pw2[66];
ll pw3[66];
int dp[LIM][N];
bool u[LIM][N];

inline ll solve(ll s, int b) {
  if (s < 0)
    return 0;
  if (s == 0 && b == 0) {
    //	cout << "was: 1" << '\n';
    return 1;
  }
  if (2ll * (pw2[b] - 1) <= s) {
    //	cout << "was: 2" << '\n';
    return pw3[b];
  }

  if (s > N || b > LIM) {
    // cout << (b > LIM) << '\n';
    int res = (solve(s, b - 1) + solve(s - pw2[b], b - 1) +
               solve(s - pw2[b - 1], b - 1)) %
              mod;

    return res;
  }

  int &res = dp[b][s];
  // cout << res << ":\n";
  if (u[b][s])
    return res;
  u[b][s] = 1;

  res = (solve(s, b - 1) + solve(s - pw2[b], b - 1) +
         solve(s - pw2[b - 1], b - 1)) %
        mod;
  return res;
}

int main() {
  SpeedForce;
  cin >> n;
  pw2[0] = pw3[0] = 1;
  for (int i = 1; i <= 61; i++) {
    pw2[i] = (1ll << i);
    pw3[i] = (pw3[i - 1] * 3ll) % mod;
  }

  cout << solve(n, 60) << '\n';

  return Accepted;
}

// B...a

Fixed submission:
#include <bits/stdc++.h>

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define _USE_MATH_DEFINES_
#define ll long long
#define ld long double
#define Accepted 0
#define pb push_back
#define mp make_pair
#define sz(x) (int)(x.size())
#define every(x) x.begin(), x.end()
#define F first
#define S second
#define lb lower_bound
#define ub upper_bound
#define For(i, x, y) for (ll i = x; i <= y; i++)
#define FOr(i, x, y) for (ll i = x; i >= y; i--)
#define SpeedForce ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
// ROAD to... Red

inline void Input_Output() {
  // freopen(".in", "r", stdin);
  // freopen(".out", "w", stdout);
}

const double eps = 0.000001;
const ld pi = acos(-1);
const int maxn = 1e7 + 9;
const int mod = 1e9 + 7;
const ll MOD = 1e18 + 9;
const ll INF = 1e18 + 123;
const int inf = 2e9 + 11;
const int mxn = 1e6 + 9;
const int N = 5e5 + 123;
const int LIM = 52;
const int pri = 997;
const int Magic = 2101;

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

ll n;
ll pw2[66];
ll pw3[66];
int dp[LIM][N];
bool u[LIM][N];

inline ll solve(ll s, int b) {
  if (s < 0)
    return 0;
  if (s == 0 && b == 0) {
    //	cout << "was: 1" << '\n';
    return 1;
  }
  if (2ll * (pw2[b] - 1) <= s) {
    //	cout << "was: 2" << '\n';
    return pw3[b];
  }

  if (s >= N || b >= LIM) {
    // cout << (b > LIM) << '\n';
    int res = (solve(s, b - 1) + solve(s - pw2[b], b - 1) +
               solve(s - pw2[b - 1], b - 1)) %
              mod;

    return res;
  }

  int &res = dp[b][s];
  // cout << res << ":\n";
  if (u[b][s])
    return res;
  u[b][s] = 1;

  res = (solve(s, b - 1) + solve(s - pw2[b], b - 1) +
         solve(s - pw2[b - 1], b - 1)) %
        mod;
  return res;
}

int main() {
  SpeedForce;
  cin >> n;
  pw2[0] = pw3[0] = 1;
  for (int i = 1; i <= 61; i++) {
    pw2[i] = (1ll << i);
    pw3[i] = (pw3[i - 1] * 3ll) % mod;
  }

  cout << solve(n, 60) << '\n';

  return Accepted;
}

// B...a