Problem p00817 (C++)

Buggy submission (status: 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);
}

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

using Edge = tuple<int, bool>;
int n, p1, p2;
vector<vector<Edge>> edge;
vector<bool> used;

void dfs(int v, bool is_kind, map<int, bool> &dic) {
  if (used[v])
    return;
  used[v] = true;

  dic[v] = is_kind;

  for (auto &e : edge[v]) {
    int nv;
    bool info;
    tie(nv, info) = e;

    bool nis_kind = is_kind ^ info;
    dfs(nv, nis_kind, dic);
  }
}

signed main(void) {
  for (int m; cin >> m >> p1 >> p2, m or p1 or p2;) {
    n = p1 + p2;

    edge = vector<vector<Edge>>(n);
    used = vector<bool>(n);

    rep(loop, m) {
      int x, y;
      string a;
      cin >> x >> y >> a;
      x--, y--;

      cerr << x << " " << y << endl;
      edge[x].push_back(Edge(y, a == "no"));
      edge[y].push_back(Edge(x, a == "no"));
    }

    vector<vi> dp(n + 1, vi(p1 + 1));
    vector<map<int, bool>> dic(n + 1);
    vector<vector<pair<int, bool>>> pre_idx(n + 1,
                                            vector<pair<int, bool>>(p1 + 1));
    dp[0][0] = 1;

    int idx = 0;

    rep(i, n) {
      if (used[i])
        continue;

      idx++;

      dfs(i, true, dic[idx]);

      int cnt_kind = 0, cnt_rev = 0;
      for (auto &e : dic[idx]) {
        if (e.second)
          cnt_kind++;
        else
          cnt_rev++;
      }

      rep(j, p1 + 1) {
        if (j - cnt_kind >= 0 and
            chmax(dp[idx][j], dp[idx][j] + dp[idx - 1][j - cnt_kind])) {
          pre_idx[idx][j] = make_pair(j - cnt_kind, true);
        }

        if (j - cnt_rev >= 0 and
            chmax(dp[idx][j], dp[idx][j] + dp[idx - 1][j - cnt_rev])) {
          pre_idx[idx][j] = make_pair(j - cnt_rev, false);
        }
      }
    }

    if (dp[idx][p1] != 1) {
      cout << "no" << endl;
      continue;
    }

    set<int> res;
    while (idx > 0) {
      for (auto &e : dic[idx]) {
        if (not(pre_idx[idx][p1].second ^ e.second))
          res.insert(e.first);
      }
      p1 = pre_idx[idx][p1].first;
      idx--;
    }

    for (auto &e : res) {
      cout << e + 1 << endl;
    }
    cout << "end" << endl;
  }

  return 0;
}

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);
}

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

using Edge = tuple<int, bool>;
int n, p1, p2;
vector<vector<Edge>> edge;
vector<bool> used;

void dfs(int v, bool is_kind, map<int, bool> &dic) {
  if (used[v])
    return;
  used[v] = true;

  dic[v] = is_kind;

  for (auto &e : edge[v]) {
    int nv;
    bool info;
    tie(nv, info) = e;

    bool nis_kind = is_kind ^ info;
    dfs(nv, nis_kind, dic);
  }
}

signed main(void) {
  for (int m; cin >> m >> p1 >> p2, m or p1 or p2;) {
    n = p1 + p2;

    edge = vector<vector<Edge>>(n);
    used = vector<bool>(n);

    rep(loop, m) {
      int x, y;
      string a;
      cin >> x >> y >> a;
      x--, y--;

      edge[x].push_back(Edge(y, a == "no"));
      edge[y].push_back(Edge(x, a == "no"));
    }

    vector<vi> dp(n + 1, vi(p1 + 1));
    vector<map<int, bool>> dic(n + 1);
    vector<vector<pair<int, bool>>> pre_idx(n + 1,
                                            vector<pair<int, bool>>(p1 + 1));
    dp[0][0] = 1;

    int idx = 0;

    rep(i, n) {
      if (used[i])
        continue;

      idx++;

      dfs(i, true, dic[idx]);

      int cnt_kind = 0, cnt_rev = 0;
      for (auto &e : dic[idx]) {
        if (e.second)
          cnt_kind++;
        else
          cnt_rev++;
      }

      rep(j, p1 + 1) {
        if (j - cnt_kind >= 0 and
            chmax(dp[idx][j], dp[idx][j] + dp[idx - 1][j - cnt_kind])) {
          pre_idx[idx][j] = make_pair(j - cnt_kind, true);
        }

        if (j - cnt_rev >= 0 and
            chmax(dp[idx][j], dp[idx][j] + dp[idx - 1][j - cnt_rev])) {
          pre_idx[idx][j] = make_pair(j - cnt_rev, false);
        }
      }
    }

    if (dp[idx][p1] != 1) {
      cout << "no" << endl;
      continue;
    }

    set<int> res;
    while (idx > 0) {
      for (auto &e : dic[idx]) {
        if (not(pre_idx[idx][p1].second ^ e.second))
          res.insert(e.first);
      }
      p1 = pre_idx[idx][p1].first;
      idx--;
    }

    for (auto &e : res) {
      cout << e + 1 << endl;
    }
    cout << "end" << endl;
  }

  return 0;
}