Problem p02930 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
#define ll long long
#define ull unsigned long long

#if 0
const int MOD = ;

inline int lgput(int a, int b) {
    int ans = 1;
    while(b > 0) {
        if(b & 1) ans = (1LL * ans * a) % MOD;
        b >>= 1;
        a = (1LL * a * a) % MOD;
    }
    return ans;
}

inline void mod(int &x) {
    if(x >= MOD)
        x -= MOD;
}

inline void add(int &x, int y) {
    x += y;
    mod(x);
}

inline void sub(int &x, int y) {
    x += MOD - y;
    mod(x);
}

inline void mul(int &x, int y) {
    x = (1LL * x * y) % MOD;
}

inline int inv(int x) {
    return lgput(x, MOD - 2);
}
#endif

#if 0
int fact[], invfact[];

inline void prec(int n) {
    fact[0] = 1;
    for(int i = 1; i <= n; i++) {
        fact[i] = (1LL * fact[i - 1] * i) % MOD;
    }
    invfact[n] = lgput(fact[n], MOD - 2);
    for(int i = n - 1; i >= 0; i--) {
        invfact[i] = (1LL * invfact[i + 1] * (i + 1)) % MOD;
    }
}

inline int comb(int n, int k) {
    if(n < k) return 0;
    return (1LL * fact[n] * (1LL * invfact[k] * invfact[n - k] % MOD)) % MOD;
}
#endif

using namespace std;

const int MAXN = 500;

int mat[MAXN + 1][MAXN + 1];

void solve(int l, int r, int cnt) {
  if (l == r) {
    return;
  }

  int mid = (l + r) / 2;
  solve(l, mid, cnt + 1);
  solve(mid + 1, r, cnt + 1);

  int i, j;
  for (i = l; i <= mid; i++) {
    for (j = mid + 1; j <= r; j++) {
      mat[i][j] = cnt;
    }
  }
}

int main() {
#if 0
    ifstream cin("A.in");
    ofstream cout("A.out");
#endif
  int i, j, n;
  ios::sync_with_stdio(false);
  cin.tie(0), cout.tie(0);

  cin >> n;
  int aux = n;
  while ((n & (n - 1)) > 0) {
    n++;
  }
  solve(1, n, 1);
  n = aux;
  for (i = 1; i <= n; i++) {
    for (j = i + 1; j <= n; j++) {
      cout << mat[i][j] << " ";
    }
    cout << "\n";
  }

  return 0;
}


Fixed submission:
#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
#define ll long long
#define ull unsigned long long

#if 0
const int MOD = ;

inline int lgput(int a, int b) {
    int ans = 1;
    while(b > 0) {
        if(b & 1) ans = (1LL * ans * a) % MOD;
        b >>= 1;
        a = (1LL * a * a) % MOD;
    }
    return ans;
}

inline void mod(int &x) {
    if(x >= MOD)
        x -= MOD;
}

inline void add(int &x, int y) {
    x += y;
    mod(x);
}

inline void sub(int &x, int y) {
    x += MOD - y;
    mod(x);
}

inline void mul(int &x, int y) {
    x = (1LL * x * y) % MOD;
}

inline int inv(int x) {
    return lgput(x, MOD - 2);
}
#endif

#if 0
int fact[], invfact[];

inline void prec(int n) {
    fact[0] = 1;
    for(int i = 1; i <= n; i++) {
        fact[i] = (1LL * fact[i - 1] * i) % MOD;
    }
    invfact[n] = lgput(fact[n], MOD - 2);
    for(int i = n - 1; i >= 0; i--) {
        invfact[i] = (1LL * invfact[i + 1] * (i + 1)) % MOD;
    }
}

inline int comb(int n, int k) {
    if(n < k) return 0;
    return (1LL * fact[n] * (1LL * invfact[k] * invfact[n - k] % MOD)) % MOD;
}
#endif

using namespace std;

const int MAXN = 512;

int mat[MAXN + 1][MAXN + 1];

void solve(int l, int r, int cnt) {
  if (l == r) {
    return;
  }

  int mid = (l + r) / 2;
  solve(l, mid, cnt + 1);
  solve(mid + 1, r, cnt + 1);

  int i, j;
  for (i = l; i <= mid; i++) {
    for (j = mid + 1; j <= r; j++) {
      mat[i][j] = cnt;
    }
  }
}

int main() {
#if 0
    ifstream cin("A.in");
    ofstream cout("A.out");
#endif
  int i, j, n;
  ios::sync_with_stdio(false);
  cin.tie(0), cout.tie(0);

  cin >> n;
  int aux = n;
  while ((n & (n - 1)) > 0) {
    n++;
  }
  solve(1, n, 1);
  n = aux;
  for (i = 1; i <= n; i++) {
    for (j = i + 1; j <= n; j++) {
      cout << mat[i][j] << " ";
    }
    cout << "\n";
  }

  return 0;
}