Problem p01275 (C++) — buggy submission, verdict: Memory Limit Exceeded

#include <bits/stdc++.h>

using namespace std;

inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T> inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}
template <class T> inline T sqr(T x) { return x * x; }

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;

#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define pb push_back
#define mp make_pair
#define each(i, c)                                                             \\
  for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define exist(s, e) ((s).find(e) != (s).end())
#define range(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(i, n) range(i, 0, n)
#define clr(a, b) memset((a), (b), sizeof(a))
#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;

const double eps = 1e-10;
const double pi = acos(-1.0);
const ll INF = 1LL << 62;
const int inf = 1 << 29;

signed main(void) {
  for (int n; cin >> n, n;) {

    //(ダイアル) -> (回数)
    map<string, int> minDist;

    string before, after;
    cin >> before >> after;

    queue<string> q;
    q.push(before);
    minDist[before] = 0;

#define F first
#define S second

    int res = inf;
    while (!q.empty()) {
      string cur_dial = q.front();
      q.pop();

      int cur_cnt = minDist[cur_dial];

      if (cur_dial == after) {
        res = cur_cnt;
        break;
      }

      int cur_ind = 0;
      while (cur_dial[cur_ind] == after[cur_ind])
        cur_ind++;

      if (cur_ind == n)
        continue;

      int delta = (after.at(cur_ind) - cur_dial.at(cur_ind) + 10) % 10;

      range(i, cur_ind, n) {
        cur_dial[i] = (cur_dial[i] - '0' + 10 + delta) % 10 + '0';

        if (minDist.find(cur_dial) != minDist.end())
          continue;

        minDist[cur_dial] = cur_cnt + 1;
        q.push(cur_dial);
      }
    }

    cout << res << endl;
  }

  return 0;
}

Error: MLE

Fixed submission:

#include <bits/stdc++.h>

using namespace std;

inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T> inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}
template <class T> inline T sqr(T x) { return x * x; }

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;

#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define pb push_back
#define mp make_pair
#define each(i, c)                                                             \\
  for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define exist(s, e) ((s).find(e) != (s).end())
#define range(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(i, n) range(i, 0, n)
#define clr(a, b) memset((a), (b), sizeof(a))
#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;

const double eps = 1e-10;
const double pi = acos(-1.0);
const ll INF = 1LL << 62;
const int inf = 1 << 29;

//(回数, ダイアル)
typedef pair<int, string> State;

signed main(void) {
  for (int n; cin >> n, n;) {
    string before, after;
    cin >> before >> after;

    queue<State> q;
    q.push(mp(0, before));

#define F first
#define S second

    int res = inf;
    while (!q.empty()) {
      int cur_cnt = q.front().F;
      string cur_dial = q.front().S;
      q.pop();

      if (cur_dial == after) {
        res = min(res, cur_cnt);
        continue;
      }

      int cur_ind = 0;
      while (cur_dial[cur_ind] == after[cur_ind])
        cur_ind++;

      if (cur_ind == n)
        continue;

      int delta = (after.at(cur_ind) - cur_dial.at(cur_ind) + 10) % 10;
      if (delta == 0) {
        q.push(mp(cur_cnt, cur_dial));
      }

      range(i, cur_ind, n) {
        cur_dial[i] += delta;
        if (!isdigit(cur_dial.at(i)))
          cur_dial[i] -= 10;

        q.push(mp(cur_cnt + 1, cur_dial));
      }
    }

    cout << res << endl;
  }

  return 0;
}