Problem p00262 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <bitset>
#include <cassert>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
const int dy[] = {-1, 0, 1, 0}, dx[] = {0, 1, 0, -1};
// adjust problem by problem
const double EPS = 1e-8;
const double PI = acos(-1.0);
#ifdef __GNUC__
int popcount(int n) { return __builtin_popcount(n); }
int popcount(ll n) { return __builtin_popcountll(n); }
#endif
#ifndef __GNUC__
template <class T> int popcount(T n) {
  int cnt = 0;
  while (n) {
    if (n % 2)
      cnt++;
    n /= 2;
  }
  return cnt;
}
#endif
template <class T> int SIZE(T a) { return a.size(); }
template <class T> string IntToString(T num) {
  string res;
  stringstream ss;
  ss << num;
  return ss.str();
}
template <class T> T StringToInt(string str) {
  T res = 0;
  for (int i = 0; i < SIZE(str); i++)
    res = (res * 10 + str[i] - '0');
  return res;
}
template <class T> T gcd(T a, T b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}
template <class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
template <class T> void PrintSeq(T &a, int sz) {
  for (int i = 0; i < sz; i++) {
    cout << a[i];
    if (sz == i + 1)
      cout << endl;
    else
      cout << ' ';
  }
}
bool EQ(double a, double b) { return abs(a - b) < EPS; }
void fastStream() {
  cin.tie(0);
  std::ios_base::sync_with_stdio(0);
}
vector<string> split(string str, char del) {
  vector<string> res;
  for (int i = 0, s = 0; i < SIZE(str); i++) {
    if (str[i] == del) {
      if (i - s != 0)
        res.push_back(str.substr(s, i - s));
      s = i + 1;
    } else if (i == SIZE(str) - 1) {
      res.push_back(str.substr(s));
    }
  }
  return res;
}

int N;
int bs[100001];
int main() {
  while (cin >> N && N) {
    int sum = 0;
    for (int i = 0; i < N; i++) {
      cin >> bs[i];
      sum += bs[i];
    }
    bool ok = false;
    int k = 0;
    for (k = 1; k * (k + 1) / 2 <= sum; k++) {
      if (k * (k + 1) / 2 == sum) {
        ok = true;
        break;
      }
    }
    int sz = N;
    if (!ok)
      cout << -1 << endl;
    else {
      int iter = 0;
      for (iter = 0; iter < 10000; iter++) {
        ok = true;
        // check
        for (int i = 0; i < k; i++)
          if (bs[i] != i + 1)
            ok = false;
        if (ok)
          break;
        // remake
        int cnt = 0;
        int val = 0;
        for (int i = 0; i < sz; i++) {
          if (bs[i] == 0)
            cnt++;
          else {
            bs[i]--;
            val++;
          }
        }
        int pos = 0;
        for (int i = 0; i < sz; i++)
          if (bs[i] != 0)
            bs[pos++] = bs[i];
        bs[pos++] = val;
        sz = pos;
      }
      if (iter == 10000)
        cout << -1 << endl;
      else
        cout << iter << endl;
    }
  }

  return 0;
}

Error: 0

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cassert>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
const int dy[] = {-1, 0, 1, 0}, dx[] = {0, 1, 0, -1};
// adjust problem by problem
const double EPS = 1e-8;
const double PI = acos(-1.0);
#ifdef __GNUC__
int popcount(int n) { return __builtin_popcount(n); }
int popcount(ll n) { return __builtin_popcountll(n); }
#endif
#ifndef __GNUC__
template <class T> int popcount(T n) {
  int cnt = 0;
  while (n) {
    if (n % 2)
      cnt++;
    n /= 2;
  }
  return cnt;
}
#endif
template <class T> int SIZE(T a) { return a.size(); }
template <class T> string IntToString(T num) {
  string res;
  stringstream ss;
  ss << num;
  return ss.str();
}
template <class T> T StringToInt(string str) {
  T res = 0;
  for (int i = 0; i < SIZE(str); i++)
    res = (res * 10 + str[i] - '0');
  return res;
}
template <class T> T gcd(T a, T b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}
template <class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
template <class T> void PrintSeq(T &a, int sz) {
  for (int i = 0; i < sz; i++) {
    cout << a[i];
    if (sz == i + 1)
      cout << endl;
    else
      cout << ' ';
  }
}
bool EQ(double a, double b) { return abs(a - b) < EPS; }
void fastStream() {
  cin.tie(0);
  std::ios_base::sync_with_stdio(0);
}
vector<string> split(string str, char del) {
  vector<string> res;
  for (int i = 0, s = 0; i < SIZE(str); i++) {
    if (str[i] == del) {
      if (i - s != 0)
        res.push_back(str.substr(s, i - s));
      s = i + 1;
    } else if (i == SIZE(str) - 1) {
      res.push_back(str.substr(s));
    }
  }
  return res;
}

int N;
int bs[101];
int main() {
  while (cin >> N && N) {
    int sum = 0;
    for (int i = 0; i < N; i++) {
      cin >> bs[i];
      sum += bs[i];
    }
    bool ok = false;
    int k = 0;
    for (k = 1; k * (k + 1) / 2 <= sum; k++) {
      if (k * (k + 1) / 2 == sum) {
        ok = true;
        break;
      }
    }
    int sz = N;
    if (!ok)
      cout << -1 << endl;
    else {
      int iter = 0;
      for (iter = 0; iter < 10000; iter++) {
        ok = true;
        // check
        for (int i = 0; i < k; i++)
          if (bs[i] != i + 1)
            ok = false;
        if (ok)
          break;
        // remake
        int cnt = 0;
        int val = 0;
        for (int i = 0; i < sz; i++) {
          if (bs[i] == 0)
            cnt++;
          else {
            bs[i]--;
            val++;
          }
        }
        int pos = 0;
        for (int i = 0; i < sz; i++)
          if (bs[i] != 0)
            bs[pos++] = bs[i];
        bs[pos++] = val;
        sz = pos;
      }
      if (iter == 10000)
        cout << -1 << endl;
      else
        cout << iter << endl;
    }
  }

  return 0;
}