Problem p03142 (C++)

Buggy submission (status: Runtime Error):
#include <algorithm>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <math.h>
#include <queue>
#include <regex>
#include <set>
#include <stack>
#include <stdio.h>
#include <string>
#include <utility>
#include <vector>
using namespace std;
using pii = pair<int, int>;
using ll = long long;
using ld = long double;
#define pb push_back
#define mp make_pair
#define sc second
#define fr first
#define stpr setprecision
#define cYES cout << "YES" << endl
#define cNO cout << "NO" << endl
#define cYes cout << "Yes" << endl
#define cNo cout << "No" << endl
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define Rep(i, a, b) for (ll i = (a); i < (b); ++i)
#define rrep(i, n) for (int i = n - 1; i >= 0; i--)
#define rRep(i, a, b) for (int i = a; i >= b; i--)
#define crep(i) for (char i = 'a'; i <= 'z'; ++i)
#define psortsecond(A, N)                                                      \
  sort(A, A + N,                                                               \
       [](const pii &a, const pii &b) { return a.second < b.second; });
#define ALL(x) (x).begin(), (x).end()
#define debug(v)                                                               \
  cout << #v << ":";                                                           \
  for (auto x : v) {                                                           \
    cout << x << ' ';                                                          \
  }                                                                            \
  cout << endl;
#define endl '\n'
int ctoi(const char c) {
  if ('0' <= c && c <= '9')
    return (c - '0');
  return -1;
}
ll gcd(ll a, ll b) { return (b == 0 ? a : gcd(b, a % b)); }
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }
constexpr ll MOD = 1000000007;
constexpr ll INF = 1000000011;
constexpr ll MOD2 = 998244353;
constexpr ll LINF = 1001002003004005006ll;
constexpr ld EPS = 10e-8;
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (auto &&x : v)
    is >> x;
  return is;
}
template <typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first;
  is >> p.second;
  return is;
}
template <typename T, typename U>
ostream &operator>>(ostream &os, const pair<T, U> &p) {
  os << p.first << ' ' << p.second;
  return os;
}
template <class T> ostream &operator<<(ostream &os, vector<T> &v) {
  for (auto i = begin(v); i != end(v); ++i) {
    if (i != begin(v))
      os << ' ';
    os << *i;
  }
  return os;
}

vector<vector<ll>> E(10007); // 各点の持つ子の情報
ll color[10007];             // 訪れ所の
bool B[100007];              // outに入ってるか否か
list<ll> out;  // トポロジカルソート済みの配列を入れる
ll N, M, a, b; // N:頂点数　M:エッジ数
ll indeg[100007]; // 各点の入次数。訪問した回数だけ減っていく。
ll parent[100007]; // 根付き木とみなした時の親

void bfs(ll s) {
  queue<ll> Q;
  Q.push(s);
  B[s] = true;
  while (!Q.empty()) {
    ll u = Q.front();
    Q.pop();
    out.pb(u);
    rep(i, E[u].size()) {
      ll v = E[u][i];
      indeg[v]--;
      if (indeg[v] == 0 && B[v] == false) {
        parent[v] = u;
        B[v] = true;
        Q.push(v);
      }
    }
  }
}

void topological_sort() {
  rep(i, N) { // 初期化
    indeg[i] = 0;
    parent[i] = 0;
  }
  rep(i, N) {
    rep(j, E[i].size()) { //  入次数を持たせる
      indeg[E[i][j]]++;
    }
  }

  rep(i, N) {
    if (indeg[i] == 0 && !B[i]) {
      parent[i] = -1;
      bfs(i);
    }
  }
}

int main() {
  cin >> N >> M;
  ll A[100007], B[100007], D[100007];
  rep(i, N) { B[i] = false; }
  M = M + N - 1;
  rep(i, M) {
    cin >> a >> b;
    a--;
    b--;
    E[a].pb(b);
  }

  topological_sort();
  ll T = 0;
  rep(i, N) { cout << parent[i] + 1 << endl; }
}

Fixed submission:
#include <algorithm>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <math.h>
#include <queue>
#include <regex>
#include <set>
#include <stack>
#include <stdio.h>
#include <string>
#include <utility>
#include <vector>
using namespace std;
using pii = pair<int, int>;
using ll = long long;
using ld = long double;
#define pb push_back
#define mp make_pair
#define sc second
#define fr first
#define stpr setprecision
#define cYES cout << "YES" << endl
#define cNO cout << "NO" << endl
#define cYes cout << "Yes" << endl
#define cNo cout << "No" << endl
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define Rep(i, a, b) for (ll i = (a); i < (b); ++i)
#define rrep(i, n) for (int i = n - 1; i >= 0; i--)
#define rRep(i, a, b) for (int i = a; i >= b; i--)
#define crep(i) for (char i = 'a'; i <= 'z'; ++i)
#define psortsecond(A, N)                                                      \
  sort(A, A + N,                                                               \
       [](const pii &a, const pii &b) { return a.second < b.second; });
#define ALL(x) (x).begin(), (x).end()
#define debug(v)                                                               \
  cout << #v << ":";                                                           \
  for (auto x : v) {                                                           \
    cout << x << ' ';                                                          \
  }                                                                            \
  cout << endl;
#define endl '\n'
int ctoi(const char c) {
  if ('0' <= c && c <= '9')
    return (c - '0');
  return -1;
}
ll gcd(ll a, ll b) { return (b == 0 ? a : gcd(b, a % b)); }
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }
constexpr ll MOD = 1000000007;
constexpr ll INF = 1000000011;
constexpr ll MOD2 = 998244353;
constexpr ll LINF = 1001002003004005006ll;
constexpr ld EPS = 10e-8;
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (auto &&x : v)
    is >> x;
  return is;
}
template <typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first;
  is >> p.second;
  return is;
}
template <typename T, typename U>
ostream &operator>>(ostream &os, const pair<T, U> &p) {
  os << p.first << ' ' << p.second;
  return os;
}
template <class T> ostream &operator<<(ostream &os, vector<T> &v) {
  for (auto i = begin(v); i != end(v); ++i) {
    if (i != begin(v))
      os << ' ';
    os << *i;
  }
  return os;
}

vector<vector<ll>> E(100007); // 各点の持つ子の情報
ll color[100007];             // 訪れ所の
bool B[100007];               // outに入ってるか否か
list<ll> out;  // トポロジカルソート済みの配列を入れる
ll N, M, a, b; // N:頂点数　M:エッジ数
ll indeg[100007]; // 各点の入次数。訪問した回数だけ減っていく。
ll parent[100007]; // 根付き木とみなした時の親

void bfs(ll s) {
  queue<ll> Q;
  Q.push(s);
  B[s] = true;
  while (!Q.empty()) {
    ll u = Q.front();
    Q.pop();
    out.pb(u);
    rep(i, E[u].size()) {
      ll v = E[u][i];
      indeg[v]--;
      if (indeg[v] == 0 && B[v] == false) {
        parent[v] = u;
        B[v] = true;
        Q.push(v);
      }
    }
  }
}

void topological_sort() {
  rep(i, N) { // 初期化
    indeg[i] = 0;
    parent[i] = 0;
  }
  rep(i, N) {
    rep(j, E[i].size()) { //  入次数を持たせる
      indeg[E[i][j]]++;
    }
  }

  rep(i, N) {
    if (indeg[i] == 0 && !B[i]) {
      parent[i] = -1;
      bfs(i);
    }
  }
}

int main() {
  cin >> N >> M;
  ll A[100007], B[100007], D[100007];
  rep(i, N) { B[i] = false; }
  M = M + N - 1;
  rep(i, M) {
    cin >> a >> b;
    a--;
    b--;
    E[a].pb(b);
  }

  topological_sort();
  ll T = 0;
  rep(i, N) { cout << parent[i] + 1 << endl; }
}