Problem p01832 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>

#define _overload(_1, _2, _3, name, ...) name
#define _rep(i, n) _range(i, 0, n)
#define _range(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define rep(...) _overload(__VA_ARGS__, _range, _rep, )(__VA_ARGS__)

#define _rrep(i, n) _rrange(i, n, 0)
#define _rrange(i, a, b) for (int i = (int)(a)-1; i >= (int)(b); --i)
#define rrep(...) _overload(__VA_ARGS__, _rrange, _rrep, )(__VA_ARGS__)

#define _all(arg) begin(arg), end(arg)
#define uniq(arg) sort(_all(arg)), (arg).erase(unique(_all(arg)), end(arg))
#define getidx(ary, key) lower_bound(_all(ary), key) - begin(ary)
#define clr(a, b) memset((a), (b), sizeof(a))
#define bit(n) (1LL << (n))

// #define DEBUG

#ifdef DEBUG
#define dump(...) fprintf(stderr, __VA_ARGS__)
#else
#define dump(...)
#endif

template <class T> bool chmax(T &a, const T &b) {
  return (a < b) ? (a = b, 1) : 0;
}
template <class T> bool chmin(T &a, const T &b) {
  return (b < a) ? (a = b, 1) : 0;
}

using namespace std;
using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;

const double EPS = 1e-10;
const double PI = acos(-1.0);
const ll inf = 1LL << 62;
const ll mod = 1000000007LL;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

ll extgcd(ll a, ll b, ll &x, ll &y) {
  x = 1, y = 0;
  ll g = a;
  if (b != 0)
    g = extgcd(b, a % b, y, x), y -= a / b * x;
  return g;
}
ll ADD(const ll &a, const ll &b, const ll &mod) { return (a + b) % mod; }
ll SUB(const ll &a, const ll &b, const ll &mod) { return (a - b + mod) % mod; }
ll MUL(const ll &a, const ll &b, const ll &mod) { return (1LL * a * b) % mod; }
ll DIV(const ll &a, const ll &b, const ll &mod) {
  ll x, y;
  extgcd(b, mod, x, y);
  return MUL(a, (x + mod) % mod, mod);
}

random_device rd;
mt19937 mt(rd());
uniform_int_distribution<int> dice(1, 6);
uniform_real_distribution<double> score(0.0, 10.0);

int n;
int len;
int idx;
string in;

void Print(vi &tbl) {
  rep(i, n) {
    rep(j, n) { cerr << tbl[i * n + j] << " "; }
    cerr << endl;
  }
  cerr << "-----" << endl;
}

void calc(vi &tbl, vi &dst) {
  vi ndst = dst;
  rep(i, n * n) { ndst[i] = dst[tbl[i]]; }
  dst = ndst;
}

void power(vi &tbl, int m, vi &dst) {
  vi cur = tbl;
  while (m >= 1) {
    if (m % 2 == 1) {
      calc(cur, dst);
    }
    calc(cur, cur);
    m /= 2;
  }
}

void operate(char op, int k, vi &dst) {
  k--;
  vi tbl(n * n);
  rep(i, n * n) tbl[i] = i;

  int tmp;
  switch (op) {
  case 'L':
    tmp = tbl[k * n];
    rep(i, n - 1) { tbl[k * n + i] = tbl[k * n + i + 1]; }
    tbl[(k + 1) * n - 1] = tmp;
    break;
  case 'R':
    tmp = tbl[(k + 1) * n - 1];
    rrep(i, n, 1) { tbl[k * n + i] = tbl[k * n + i - 1]; }
    tbl[k * n] = tmp;
    break;
  case 'U':
    tmp = tbl[k];
    rep(i, n - 1) { tbl[n * i + k] = tbl[n * (i + 1) + k]; }
    tbl[n * (n - 1) + k] = tmp;
    break;
  case 'D':
    tmp = tbl[n * (n - 1) + k];
    rrep(i, n, 1) { tbl[n * i + k] = tbl[n * (i - 1) + k]; }
    tbl[k] = tmp;
    break;
  default:
    assert(false);
    break;
  }

  power(tbl, 1, dst);
}

vi parse() {
  vi ret(n * n);
  rep(i, n * n) ret[i] = i;

  while (idx < len) {
    if (in[idx] == ')') {
      break;
    } else if (in[idx] == '(') {
      assert(in[idx++] == '(');
      vi tbl = parse();
      assert(in[idx++] == ')');

      int times = 0;
      while (isdigit(in[idx])) {
        times = 10 * times + (int)(in[idx] - '0');
        idx++;
      }
      power(tbl, times, ret);
    } else {
      char op = in[idx];
      idx++;
      int k = 0;
      while (isdigit(in[idx])) {
        k = 10 * k + (int)(in[idx] - '0');
        idx++;
      }
      operate(op, k, ret);
    }
  }

  return ret;
}

int main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);

  cin >> n >> len;
  cin >> in;
  if (in[0] != '(')
    in = "(" + in + ")1";

  auto tbl = parse();

  vi res(n * n);
  rep(i, n * n) { res[i] = i + 1; }
  calc(tbl, res);

  rep(i, n) {
    rep(j, n) { cout << (j ? " " : "") << res[i * n + j]; }
    cout << endl;
  }

  return 0;
}

Error: 0
2 0 1 
3 4 5 
6 7 8 
-----
2 0 1 
3 4 5 
6 7 8 
-----


Fixed submission:

#include <bits/stdc++.h>

#define _overload(_1, _2, _3, name, ...) name
#define _rep(i, n) _range(i, 0, n)
#define _range(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define rep(...) _overload(__VA_ARGS__, _range, _rep, )(__VA_ARGS__)

#define _rrep(i, n) _rrange(i, n, 0)
#define _rrange(i, a, b) for (int i = (int)(a)-1; i >= (int)(b); --i)
#define rrep(...) _overload(__VA_ARGS__, _rrange, _rrep, )(__VA_ARGS__)

#define _all(arg) begin(arg), end(arg)
#define uniq(arg) sort(_all(arg)), (arg).erase(unique(_all(arg)), end(arg))
#define getidx(ary, key) lower_bound(_all(ary), key) - begin(ary)
#define clr(a, b) memset((a), (b), sizeof(a))
#define bit(n) (1LL << (n))

// #define DEBUG

#ifdef DEBUG
#define dump(...) fprintf(stderr, __VA_ARGS__)
#else
#define dump(...)
#endif

template <class T> bool chmax(T &a, const T &b) {
  return (a < b) ? (a = b, 1) : 0;
}
template <class T> bool chmin(T &a, const T &b) {
  return (b < a) ? (a = b, 1) : 0;
}

using namespace std;
using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;

const double EPS = 1e-10;
const double PI = acos(-1.0);
const ll inf = 1LL << 62;
const ll mod = 1000000007LL;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

ll extgcd(ll a, ll b, ll &x, ll &y) {
  x = 1, y = 0;
  ll g = a;
  if (b != 0)
    g = extgcd(b, a % b, y, x), y -= a / b * x;
  return g;
}
ll ADD(const ll &a, const ll &b, const ll &mod) { return (a + b) % mod; }
ll SUB(const ll &a, const ll &b, const ll &mod) { return (a - b + mod) % mod; }
ll MUL(const ll &a, const ll &b, const ll &mod) { return (1LL * a * b) % mod; }
ll DIV(const ll &a, const ll &b, const ll &mod) {
  ll x, y;
  extgcd(b, mod, x, y);
  return MUL(a, (x + mod) % mod, mod);
}

random_device rd;
mt19937 mt(rd());
uniform_int_distribution<int> dice(1, 6);
uniform_real_distribution<double> score(0.0, 10.0);

int n;
int len;
int idx;
string in;

void Print(vi &tbl) {
  rep(i, n) {
    rep(j, n) { cerr << tbl[i * n + j] << " "; }
    cerr << endl;
  }
  cerr << "-----" << endl;
}

void calc(vi &tbl, vi &dst) {
  vi ndst = dst;
  rep(i, n * n) { ndst[i] = dst[tbl[i]]; }
  dst = ndst;
}

void power(vi &tbl, int m, vi &dst) {
  vi cur = tbl;
  while (m >= 1) {
    if (m % 2 == 1) {
      calc(cur, dst);
    }
    calc(cur, cur);
    m /= 2;
  }
}

void operate(char op, int k, vi &dst) {
  k--;
  vi tbl(n * n);
  rep(i, n * n) tbl[i] = i;

  int tmp;
  switch (op) {
  case 'L':
    tmp = tbl[k * n];
    rep(i, n - 1) { tbl[k * n + i] = tbl[k * n + i + 1]; }
    tbl[(k + 1) * n - 1] = tmp;
    break;
  case 'R':
    tmp = tbl[(k + 1) * n - 1];
    rrep(i, n, 1) { tbl[k * n + i] = tbl[k * n + i - 1]; }
    tbl[k * n] = tmp;
    break;
  case 'U':
    tmp = tbl[k];
    rep(i, n - 1) { tbl[n * i + k] = tbl[n * (i + 1) + k]; }
    tbl[n * (n - 1) + k] = tmp;
    break;
  case 'D':
    tmp = tbl[n * (n - 1) + k];
    rrep(i, n, 1) { tbl[n * i + k] = tbl[n * (i - 1) + k]; }
    tbl[k] = tmp;
    break;
  default:
    assert(false);
    break;
  }

  power(tbl, 1, dst);
}

vi parse() {
  vi ret(n * n);
  rep(i, n * n) ret[i] = i;

  while (idx < len) {
    if (in[idx] == ')') {
      break;
    } else if (in[idx] == '(') {
      assert(in[idx++] == '(');
      vi tbl = parse();
      assert(in[idx++] == ')');

      int times = 0;
      while (isdigit(in[idx])) {
        times = 10 * times + (int)(in[idx] - '0');
        idx++;
      }
      power(tbl, times, ret);
      Print(tbl);
    } else {
      char op = in[idx];
      idx++;
      int k = 0;
      while (isdigit(in[idx])) {
        k = 10 * k + (int)(in[idx] - '0');
        idx++;
      }
      operate(op, k, ret);
      Print(ret);
    }
  }

  return ret;
}

int main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);

  cin >> n >> len;
  cin >> in;
  if (in[0] != '(')
    in = "(" + in + ")1";

  auto tbl = parse();

  vi res(n * n);
  rep(i, n * n) { res[i] = i + 1; }
  calc(tbl, res);

  rep(i, n) {
    rep(j, n) { cout << (j ? " " : "") << res[i * n + j]; }
    cout << endl;
  }

  return 0;
}