Problem p03769 (C++)

Buggy submission (status: Runtime Error):
// tzl ak IOI!

#include <bits/stdc++.h>

#define HEAP priority_queue
#define rep(i, n) for (int i = 0, _end_ = (n); i < _end_; ++i)
#define per(i, n) for (int i = (n)-1; i >= 0; --i)
#define forn(i, l, r) for (int i = (l), _end_ = (r); i <= _end_; ++i)
#define nrof(i, r, l) for (int i = (r), _end_ = (l); i >= _end_; --i)
#define FOR(a, b) for (auto(a) : (b))
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define X first
#define Y second
#define eps 1e-6
#define pi 3.1415926535897932384626433832795
#define SZ(x) (int)x.size()
#define ALL(x) x.begin(), x.end()
#define FILL(a, b) memset((a), (b), sizeof((a)))
#define MCPY(a, b) memcpy((a), (b), sizeof((b)))

using namespace std;

typedef long long LL;
typedef double flt;
typedef vector<int> vi;
typedef vector<LL> vl;
typedef pair<int, int> pii;
typedef pair<int, LL> pil;
typedef pair<LL, int> pli;
typedef pair<LL, LL> pll;
typedef vector<pil> vil;
typedef vector<pii> vii;
typedef vector<pli> vli;
typedef vector<pll> vll;

const int iinf = 1e9 + 7;
const LL linf = 1ll << 60;
const flt dinf = 1e60;

template <typename T> inline void scf(T &x) {
  bool f = 0;
  x = 0;
  char c = getchar();
  while ((c < '0' || c > '9') && c != '-')
    c = getchar();
  if (c == '-') {
    f = 1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    x = x * 10 + c - '0';
    c = getchar();
  }
  if (f)
    x = -x;
  return;
}

template <typename T1, typename T2> void scf(T1 &x, T2 &y) {
  scf(x);
  return scf(y);
}

template <typename T1, typename T2, typename T3> void scf(T1 &x, T2 &y, T3 &z) {
  scf(x);
  scf(y);
  return scf(z);
}

template <typename T1, typename T2, typename T3, typename T4>
void scf(T1 &x, T2 &y, T3 &z, T4 &w) {
  scf(x);
  scf(y);
  scf(z);
  return scf(w);
}

inline char mygetchar() {
  char c = getchar();
  while (c == ' ' || c == '\n')
    c = getchar();
  return c;
}

template <typename T> void chkmax(T &x, const T &y) {
  if (y > x)
    x = y;
  return;
}

template <typename T> void chkmin(T &x, const T &y) {
  if (y < x)
    x = y;
  return;
}

#ifdef ONLINE_JUDGE
#define debug(x, c) ;
#else
#define DEBUG
#define debug(x, c) cerr << #x << "=" << x << c;
#endif

void TZL();

void RANK1();

#define tzl int
#define ak main
#define IOI ()
tzl ak IOI {
#undef tzl
#undef ak
#undef IOI

  TZL();
  RANK1();

#define tzl return
#define caisi 0
#define myy ;
  tzl caisi myy
#undef tzl
#undef caisi
#undef myy
}

//---------------------------head----------------------------

const int N = 233;

LL n;
int cur = 0;
deque<int> ans;

void build(int n) {
  if (n == 1)
    return;
  if (n & 1) {
    build(n ^ 1);
    ans.push_front(++cur);
  } else {
    build(n >> 1);
    ans.pb(++cur);
  }
  return;
}

void TZL() {
  scf(n);
  build(n + 1);
  return;
}

void RANK1() {
  printf("%d\n", cur << 1);
  for (int x : ans)
    printf("%d ", x);
  forn(i, 1, cur) printf("%d ", i);
  return;
}

Fixed submission:
// tzl ak IOI!

#include <bits/stdc++.h>

#define HEAP priority_queue
#define rep(i, n) for (int i = 0, _end_ = (n); i < _end_; ++i)
#define per(i, n) for (int i = (n)-1; i >= 0; --i)
#define forn(i, l, r) for (int i = (l), _end_ = (r); i <= _end_; ++i)
#define nrof(i, r, l) for (int i = (r), _end_ = (l); i >= _end_; --i)
#define FOR(a, b) for (auto(a) : (b))
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define X first
#define Y second
#define eps 1e-6
#define pi 3.1415926535897932384626433832795
#define SZ(x) (int)x.size()
#define ALL(x) x.begin(), x.end()
#define FILL(a, b) memset((a), (b), sizeof((a)))
#define MCPY(a, b) memcpy((a), (b), sizeof((b)))

using namespace std;

typedef long long LL;
typedef double flt;
typedef vector<int> vi;
typedef vector<LL> vl;
typedef pair<int, int> pii;
typedef pair<int, LL> pil;
typedef pair<LL, int> pli;
typedef pair<LL, LL> pll;
typedef vector<pil> vil;
typedef vector<pii> vii;
typedef vector<pli> vli;
typedef vector<pll> vll;

const int iinf = 1e9 + 7;
const LL linf = 1ll << 60;
const flt dinf = 1e60;

template <typename T> inline void scf(T &x) {
  bool f = 0;
  x = 0;
  char c = getchar();
  while ((c < '0' || c > '9') && c != '-')
    c = getchar();
  if (c == '-') {
    f = 1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    x = x * 10 + c - '0';
    c = getchar();
  }
  if (f)
    x = -x;
  return;
}

template <typename T1, typename T2> void scf(T1 &x, T2 &y) {
  scf(x);
  return scf(y);
}

template <typename T1, typename T2, typename T3> void scf(T1 &x, T2 &y, T3 &z) {
  scf(x);
  scf(y);
  return scf(z);
}

template <typename T1, typename T2, typename T3, typename T4>
void scf(T1 &x, T2 &y, T3 &z, T4 &w) {
  scf(x);
  scf(y);
  scf(z);
  return scf(w);
}

inline char mygetchar() {
  char c = getchar();
  while (c == ' ' || c == '\n')
    c = getchar();
  return c;
}

template <typename T> void chkmax(T &x, const T &y) {
  if (y > x)
    x = y;
  return;
}

template <typename T> void chkmin(T &x, const T &y) {
  if (y < x)
    x = y;
  return;
}

#ifdef ONLINE_JUDGE
#define debug(x, c) ;
#else
#define DEBUG
#define debug(x, c) cerr << #x << "=" << x << c;
#endif

void TZL();

void RANK1();

#define tzl int
#define ak main
#define IOI ()
tzl ak IOI {
#undef tzl
#undef ak
#undef IOI

  TZL();
  RANK1();

#define tzl return
#define caisi 0
#define myy ;
  tzl caisi myy
#undef tzl
#undef caisi
#undef myy
}

//---------------------------head----------------------------

const int N = 233;

LL n;
int cur = 0;
deque<int> ans;

void build(LL n) {
  if (n == 1)
    return;
  if (n & 1) {
    build(n ^ 1);
    ans.push_front(++cur);
  } else {
    build(n >> 1);
    ans.pb(++cur);
  }
  return;
}

void TZL() {
  scf(n);
  build(n + 1);
  return;
}

void RANK1() {
  printf("%d\n", cur << 1);
  for (int x : ans)
    printf("%d ", x);
  forn(i, 1, cur) printf("%d ", i);
  return;
}