Problem p03248 (C++)

Buggy submission (status: Runtime Error):
#include <algorithm>
#include <cassert>
#include <chrono>
#include <cmath>
#include <cstdio>
#include <ctime>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;

namespace {
using Integer = long long; //__int128;
template <class T, class S> istream &operator>>(istream &is, pair<T, S> &p) {
  return is >> p.first >> p.second;
}
template <class T> istream &operator>>(istream &is, vector<T> &vec) {
  for (T &val : vec)
    is >> val;
  return is;
}
template <class T> istream &operator,(istream &is, T &val) { return is >> val; }
template <class T, class S>
ostream &operator<<(ostream &os, const pair<T, S> &p) {
  return os << p.first << " " << p.second;
}
template <class T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  for (size_t i = 0; i < vec.size(); i++)
    os << vec[i] << (i == vec.size() - 1 ? "" : " ");
  return os;
}
template <class T> ostream &operator,(ostream &os, const T &val) {
  return os << " " << val;
}

template <class H> void print(const H &head) { cout << head; }
template <class H, class... T> void print(const H &head, const T &...tail) {
  cout << head << " ";
  print(tail...);
}
template <class... T> void println(const T &...values) {
  print(values...);
  cout << endl;
}

template <class H> void eprint(const H &head) { cerr << head; }
template <class H, class... T> void eprint(const H &head, const T &...tail) {
  cerr << head << " ";
  eprint(tail...);
}
template <class... T> void eprintln(const T &...values) {
  eprint(values...);
  cerr << endl;
}

class range {
  Integer start_, end_, step_;

public:
  struct range_iterator {
    Integer val, step_;
    range_iterator(Integer v, Integer step) : val(v), step_(step) {}
    Integer operator*() { return val; }
    void operator++() { val += step_; }
    bool operator!=(range_iterator &x) {
      return step_ > 0 ? val < x.val : val > x.val;
    }
  };
  range(Integer len) : start_(0), end_(len), step_(1) {}
  range(Integer start, Integer end) : start_(start), end_(end), step_(1) {}
  range(Integer start, Integer end, Integer step)
      : start_(start), end_(end), step_(step) {}
  range_iterator begin() { return range_iterator(start_, step_); }
  range_iterator end() { return range_iterator(end_, step_); }
};

inline string operator"" _s(const char *str, size_t size) {
  return move(string(str));
}
constexpr Integer my_pow(Integer x, Integer k, Integer z = 1) {
  return k == 0    ? z
         : k == 1  ? z * x
         : (k & 1) ? my_pow(x * x, k >> 1, z * x)
                   : my_pow(x * x, k >> 1, z);
}
constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z = 1) {
  return k == 0    ? z % M
         : k == 1  ? z * x % M
         : (k & 1) ? my_pow_mod(x * x % M, k >> 1, M, z * x % M)
                   : my_pow_mod(x * x % M, k >> 1, M, z);
}
constexpr unsigned long long operator"" _ten(unsigned long long value) {
  return my_pow(10, value);
}

inline int k_bit(Integer x, int k) { return (x >> k) & 1; } // 0-indexed

mt19937 mt(chrono::duration_cast<chrono::nanoseconds>(
               chrono::steady_clock::now().time_since_epoch())
               .count());

template <class T> string join(const vector<T> &v, const string &sep) {
  stringstream ss;
  for (size_t i = 0; i < v.size(); i++) {
    if (i > 0)
      ss << sep;
    ss << v[i];
  }
  return ss.str();
}

inline string operator*(string s, int k) {
  string ret;
  while (k) {
    if (k & 1)
      ret += s;
    s += s;
    k >>= 1;
  }
  return ret;
}
} // namespace
constexpr long long mod = 9_ten + 7;

int main() {
  string s;
  cin >> s;

  if (s == "10") {
    println(1, 2);
    return 0;
  }

  int n = s.size();
  if (s.back() == '1') {
    println(-1);
    return 0;
  }
  if (s.front() == '0') {
    println(-1);
    return 0;
  }

  for (int i = 0; i < n - 1; i++) {
    if (s[i] != s[n - 1 - i - 1]) {
      println(-1);
      return 0;
    }
  }

  if (s[n / 2 - 1] == '1') {

    vector<pair<int, int>> res;
    int u = n / 2 - 1;
    int v = n / 2 - 2;
    res.emplace_back(u, v);

    for (int i = n / 2 - 2; i > 0; i--) {
      if (s[i] == '1') {
        res.emplace_back(v, i - 1);
        u = v;
        v = i - 1;
      } else {
        res.emplace_back(u, i - 1);
      }
    }

    for (int i = 0, j = res.size(); i < j; i++) {
      res.emplace_back(res[i].first + n / 2, res[i].second + n / 2);
    }

    res.emplace_back(n / 2 - 1, n / 2 - 1 + n / 2);

    if (n % 2 == 1) {
      res.emplace_back(n / 2 - 1, n - 1);
    }

    assert(res.size() == n - 1);

    eprintln(res.size());
    for (int i = 0; i < res.size(); i++) {
      println(res[i].first + 1, res[i].second + 1);
    }

  } else {
    vector<pair<int, int>> res;
    int u0 = 0, u1 = 0;
    int v0 = 1, v1 = 2;
    int w = 3;
    res.emplace_back(u0, v0);
    res.emplace_back(u1, v1);
    if (n % 2 == 0) {
      res.emplace_back(u0, w++);
    }

    for (int i = (n - 1) / 2 - 1; i > 0; i--) {
      if (s[i] == '0') {
        res.emplace_back(u0, w++);
        res.emplace_back(u1, w++);
      } else {
        res.emplace_back(v0, w++);
        u0 = v0;
        v0 = w - 1;
        res.emplace_back(v1, w++);
        u1 = v1;
        v1 = w - 1;
      }
    }

    assert(res.size() == n - 1);

    eprintln(res.size());
    for (int i = 0; i < res.size(); i++) {
      println(res[i].first + 1, res[i].second + 1);
    }
  }

  return 0;
}


Fixed submission:
#include <algorithm>
#include <cassert>
#include <chrono>
#include <cmath>
#include <cstdio>
#include <ctime>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;

namespace {
using Integer = long long; //__int128;
template <class T, class S> istream &operator>>(istream &is, pair<T, S> &p) {
  return is >> p.first >> p.second;
}
template <class T> istream &operator>>(istream &is, vector<T> &vec) {
  for (T &val : vec)
    is >> val;
  return is;
}
template <class T> istream &operator,(istream &is, T &val) { return is >> val; }
template <class T, class S>
ostream &operator<<(ostream &os, const pair<T, S> &p) {
  return os << p.first << " " << p.second;
}
template <class T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  for (size_t i = 0; i < vec.size(); i++)
    os << vec[i] << (i == vec.size() - 1 ? "" : " ");
  return os;
}
template <class T> ostream &operator,(ostream &os, const T &val) {
  return os << " " << val;
}

template <class H> void print(const H &head) { cout << head; }
template <class H, class... T> void print(const H &head, const T &...tail) {
  cout << head << " ";
  print(tail...);
}
template <class... T> void println(const T &...values) {
  print(values...);
  cout << endl;
}

template <class H> void eprint(const H &head) { cerr << head; }
template <class H, class... T> void eprint(const H &head, const T &...tail) {
  cerr << head << " ";
  eprint(tail...);
}
template <class... T> void eprintln(const T &...values) {
  eprint(values...);
  cerr << endl;
}

class range {
  Integer start_, end_, step_;

public:
  struct range_iterator {
    Integer val, step_;
    range_iterator(Integer v, Integer step) : val(v), step_(step) {}
    Integer operator*() { return val; }
    void operator++() { val += step_; }
    bool operator!=(range_iterator &x) {
      return step_ > 0 ? val < x.val : val > x.val;
    }
  };
  range(Integer len) : start_(0), end_(len), step_(1) {}
  range(Integer start, Integer end) : start_(start), end_(end), step_(1) {}
  range(Integer start, Integer end, Integer step)
      : start_(start), end_(end), step_(step) {}
  range_iterator begin() { return range_iterator(start_, step_); }
  range_iterator end() { return range_iterator(end_, step_); }
};

inline string operator"" _s(const char *str, size_t size) {
  return move(string(str));
}
constexpr Integer my_pow(Integer x, Integer k, Integer z = 1) {
  return k == 0    ? z
         : k == 1  ? z * x
         : (k & 1) ? my_pow(x * x, k >> 1, z * x)
                   : my_pow(x * x, k >> 1, z);
}
constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z = 1) {
  return k == 0    ? z % M
         : k == 1  ? z * x % M
         : (k & 1) ? my_pow_mod(x * x % M, k >> 1, M, z * x % M)
                   : my_pow_mod(x * x % M, k >> 1, M, z);
}
constexpr unsigned long long operator"" _ten(unsigned long long value) {
  return my_pow(10, value);
}

inline int k_bit(Integer x, int k) { return (x >> k) & 1; } // 0-indexed

mt19937 mt(chrono::duration_cast<chrono::nanoseconds>(
               chrono::steady_clock::now().time_since_epoch())
               .count());

template <class T> string join(const vector<T> &v, const string &sep) {
  stringstream ss;
  for (size_t i = 0; i < v.size(); i++) {
    if (i > 0)
      ss << sep;
    ss << v[i];
  }
  return ss.str();
}

inline string operator*(string s, int k) {
  string ret;
  while (k) {
    if (k & 1)
      ret += s;
    s += s;
    k >>= 1;
  }
  return ret;
}
} // namespace
constexpr long long mod = 9_ten + 7;

int main() {
  string s;
  cin >> s;

  if (s == "10") {
    println(1, 2);
    return 0;
  }
  if (s == "110") {
    println(1, 2);
    println(3, 2);
    return 0;
  }

  int n = s.size();
  if (s.back() == '1') {
    println(-1);
    return 0;
  }
  if (s.front() == '0') {
    println(-1);
    return 0;
  }

  for (int i = 0; i < n - 1; i++) {
    if (s[i] != s[n - 1 - i - 1]) {
      println(-1);
      return 0;
    }
  }

  if (s[n / 2 - 1] == '1') {

    vector<pair<int, int>> res;
    int u = n / 2 - 1;
    int v = n / 2 - 2;
    res.emplace_back(u, v);

    for (int i = n / 2 - 2; i > 0; i--) {
      if (s[i] == '1') {
        res.emplace_back(v, i - 1);
        u = v;
        v = i - 1;
      } else {
        res.emplace_back(u, i - 1);
      }
    }

    for (int i = 0, j = res.size(); i < j; i++) {
      res.emplace_back(res[i].first + n / 2, res[i].second + n / 2);
    }

    res.emplace_back(n / 2 - 1, n / 2 - 1 + n / 2);

    if (n % 2 == 1) {
      res.emplace_back(n / 2 - 1, n - 1);
    }

    assert(res.size() == n - 1);

    eprintln(res.size());
    for (int i = 0; i < res.size(); i++) {
      println(res[i].first + 1, res[i].second + 1);
    }

  } else {
    vector<pair<int, int>> res;
    int u0 = 0, u1 = 0;
    int v0 = 1, v1 = 2;
    int w = 3;
    res.emplace_back(u0, v0);
    res.emplace_back(u1, v1);
    if (n % 2 == 0) {
      res.emplace_back(u0, w++);
    }

    for (int i = (n - 1) / 2 - 1; i > 0; i--) {
      if (s[i] == '0') {
        res.emplace_back(u0, w++);
        res.emplace_back(u1, w++);
      } else {
        res.emplace_back(v0, w++);
        u0 = v0;
        v0 = w - 1;
        res.emplace_back(v1, w++);
        u1 = v1;
        v1 = w - 1;
      }
    }

    assert(res.size() == n - 1);

    eprintln(res.size());
    for (int i = 0; i < res.size(); i++) {
      println(res[i].first + 1, res[i].second + 1);
    }
  }

  return 0;
}