Problem p00837 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <cstdio>
#include <queue>

#define rep(i, n) for (int i = 0; i < (n); i++)

using namespace std;

int main() {
  for (int m, c, n; scanf("%d%d%d", &m, &c, &n), m;) {
    queue<int> Q[100];
    rep(i, n) {
      int sz;
      scanf("%d", &sz);
      rep(j, sz) {
        int a;
        scanf("%d", &a);
        Q[i].push(a);
      }
    }

    int ans = 0;
    deque<int> dai[10];
    while (1) {
      bool end = true;
      rep(i, n) if (!Q[i].empty()) {
        end = false;

        // 本を取る
        int book = Q[i].front();
        Q[i].pop();
        int pos = m;
        rep(j, m) if (count(dai[j].begin(), dai[j].end(), book) > 0) {
          pos = j;
          break;
        }
        if (pos < m) {
          dai[pos].erase(find(dai[pos].begin(), dai[pos].end(), book));
        }
        ans += pos + 1;

        // 本を置く
        if (dai[0].size() < c) {
          dai[0].push_back(book);
          ans += 1;
        } else {
          // step 1
          int pos2 = m;
          for (int j = 1; j < m; j++)
            if (dai[j].size() < c) {
              pos2 = j;
              break;
            }
          if (pos2 < m) {
            dai[pos2].push_back(book);
          }
          ans += pos2 + 1;

          // step 2
          int sub = dai[0].front();
          dai[0].pop_front();
          ans++;

          // step 3
          int pos3 = m;
          for (int j = 1; j < m; j++)
            if (dai[j].size() < c) {
              pos3 = j;
              break;
            }
          if (pos3 < m) {
            dai[pos3].push_back(sub);
          }
          ans += pos3 + 1;

          // step 4
          if (pos2 < m) {
            dai[pos2].erase(find(dai[pos2].begin(), dai[pos2].end(), book));
          }
          ans += pos2 + 1;

          // step 5
          dai[0].push_back(book);
          ans++;
        }
      }
      if (end)
        break;
    }

    printf("%d\\n", ans);
  }

  return 0;
}

Error: -11

Fixed submission:

#include <algorithm>
#include <cstdio>
#include <queue>

#define rep(i, n) for (int i = 0; i < (n); i++)

using namespace std;

int main() {
  for (int m, c, n; scanf("%d%d%d", &m, &c, &n), m;) {
    queue<int> Q[100];
    rep(i, n) {
      int sz;
      scanf("%d", &sz);
      rep(j, sz) {
        int a;
        scanf("%d", &a);
        Q[i].push(a);
      }
    }

    int ans = 0;
    deque<int> dai[10];
    while (1) {
      bool end = true;
      rep(i, n) if (!Q[i].empty()) {
        end = false;

        // 本を取る
        int book = Q[i].front();
        Q[i].pop();
        int pos = m;
        rep(j, m) if (count(dai[j].begin(), dai[j].end(), book) > 0) {
          pos = j;
          break;
        }
        if (pos < m) {
          dai[pos].erase(find(dai[pos].begin(), dai[pos].end(), book));
        }
        ans += pos + 1;

        // 本を置く
        if (dai[0].size() < c) {
          dai[0].push_back(book);
          ans += 1;
        } else {
          // step 1
          int pos2 = m;
          for (int j = 1; j < m; j++)
            if (dai[j].size() < c) {
              pos2 = j;
              break;
            }
          if (pos2 < m) {
            dai[pos2].push_back(book);
          }
          ans += pos2 + 1;

          // step 2
          int sub = dai[0].front();
          dai[0].pop_front();
          ans++;

          // step 3
          int pos3 = m;
          for (int j = 1; j < m; j++)
            if (dai[j].size() < c) {
              pos3 = j;
              break;
            }
          if (pos3 < m) {
            dai[pos3].push_back(sub);
          }
          ans += pos3 + 1;

          // step 4
          dai[pos2].erase(find(dai[pos2].begin(), dai[pos2].end(), book));
          ans += pos2 + 1;

          // step 5
          dai[0].push_back(book);
          ans++;
        }
      }
      if (end)
        break;
    }

    printf("%d\\n", ans);
  }

  return 0;
}