Problem p02565 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (ll i = 0; i < n; i++)
#define repl(i, l, r) for (ll i = (l); i < (r); i++)
#define per(i, n) for (ll i = n - 1; i >= 0; i--)
#define perl(i, r, l) for (ll i = r - 1; i >= l; i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x, vector<x>, greater<x>>
#define all(x) (x).begin(), (x).end()
#define CST(x) cout << fixed << setprecision(x)
#define vtpl(x, y, z) vector<tuple<x, y, z>>
#define rev(x) reverse(x);
using ll = long long;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using pl = pair<ll, ll>;
using vpl = vector<pl>;
using vvpl = vector<vpl>;
const ll MOD = 1000000007;
const ll MOD9 = 998244353;
const int inf = 1e9 + 10;
const ll INF = 4e18;
const ll dy[8] = {1, 0, -1, 0, 1, 1, -1, -1};
const ll dx[8] = {0, -1, 0, 1, 1, -1, 1, -1};
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

struct SCC {
  int n;
  vector<vector<int>> g, rg;
  vector<int> vs, cmp;
  vector<bool> used;
  SCC(int _n) {
    n = _n;
    g = vector<vector<int>>(n);
    rg = g;
    cmp = vector<int>(n);
    used = vector<bool>(n);
  }
  void add_edge(int f, int t) {
    g[f].push_back(t);
    rg[t].push_back(f);
  }
  int init() {
    rep(i, n) if (!used[i]) dfs(i);
    int k = 0;
    used = vector<bool>(n, false);
    per(i, n) {
      if (!used[vs[i]]) {
        rdfs(vs[i], k);
        k++;
      }
    }
    return k;
  }

private:
  void dfs(int v) {
    used[v] = true;
    rep(i, g[v].size()) {
      if (!used[g[v][i]])
        dfs(g[v][i]);
    }
    vs.push_back(v);
  }
  void rdfs(int v, int k) {
    used[v] = true;
    cmp[v] = k;
    rep(i, rg[v].size()) {
      if (!used[rg[v][i]]) {
        rdfs(rg[v][i], k);
      }
    }
  }
};

struct twoSAT {
  vector<bool> ans;
  twoSAT(int _n) : n(_n), graph(2 * n), ans(n) {}
  void add_edge(int i, bool x, int j, bool y) { // i=>j;
    if (!x)
      i += n;
    if (!y)
      j += n;
    graph.add_edge((i + n) % (2 * n), j);
    graph.add_edge((j + n) % (2 * n), i);
  }
  bool exe() {
    graph.init();
    rep(i, n) {
      if (graph.cmp[i] == graph.cmp[i + n])
        return false;
      else if (graph.cmp[i] > graph.cmp[i + n])
        ans[i] = true;
      else
        ans[i] = false;
    }
    return true;
  }

private:
  int n;
  SCC graph;
};

int main() {
  ll n, d;
  cin >> n >> d;
  twoSAT g(n);
  vl x(n), y(n);
  rep(i, n) cin >> x[i] >> y[i];
  rep(i, n) {
    repl(j, i + 1, n) {
      if (abs(x[i] - x[j]) < d) {
        g.add_edge(i, 0, j, 0);
      }
      if (abs(x[i] - y[j]) < d) {
        g.add_edge(i, 0, j, 1);
      }
      if (abs(y[i] - x[j]) < d) {
        g.add_edge(i, 1, j, 0);
      }
      if (abs(y[i] - y[j]) < d) {
        g.add_edge(i, 1, j, 1);
      }
    }
  }
  if (g.exe()) {
    cout << "Yes" << endl;
    rep(i, n) {
      if (g.ans[i])
        cout << x[i] << endl;
      else
        cout << y[i] << endl;
    }
  } else {
    cout << "No" << endl;
  }
}


Fixed submission:
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (ll i = 0; i < n; i++)
#define repl(i, l, r) for (ll i = (l); i < (r); i++)
#define per(i, n) for (ll i = n - 1; i >= 0; i--)
#define perl(i, r, l) for (ll i = r - 1; i >= l; i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x, vector<x>, greater<x>>
#define all(x) (x).begin(), (x).end()
#define CST(x) cout << fixed << setprecision(x)
#define vtpl(x, y, z) vector<tuple<x, y, z>>
#define rev(x) reverse(x);
using ll = long long;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using pl = pair<ll, ll>;
using vpl = vector<pl>;
using vvpl = vector<vpl>;
const ll MOD = 1000000007;
const ll MOD9 = 998244353;
const int inf = 1e9 + 10;
const ll INF = 4e18;
const ll dy[8] = {1, 0, -1, 0, 1, 1, -1, -1};
const ll dx[8] = {0, -1, 0, 1, 1, -1, 1, -1};
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

struct SCC {
  int n;
  vector<vector<int>> g, rg;
  vector<int> vs, cmp;
  vector<bool> used;
  SCC(int _n) {
    n = _n;
    g = vector<vector<int>>(n);
    rg = g;
    cmp = vector<int>(n);
    used = vector<bool>(n);
  }
  void add_edge(int f, int t) {
    g[f].push_back(t);
    rg[t].push_back(f);
  }
  int init() {
    rep(i, n) if (!used[i]) dfs(i);
    int k = 0;
    used = vector<bool>(n, false);
    per(i, n) {
      if (!used[vs[i]]) {
        rdfs(vs[i], k);
        k++;
      }
    }
    return k;
  }

private:
  void dfs(int v) {
    used[v] = true;
    rep(i, g[v].size()) {
      if (!used[g[v][i]])
        dfs(g[v][i]);
    }
    vs.push_back(v);
  }
  void rdfs(int v, int k) {
    used[v] = true;
    cmp[v] = k;
    rep(i, rg[v].size()) {
      if (!used[rg[v][i]]) {
        rdfs(rg[v][i], k);
      }
    }
  }
};

struct twoSAT {
  vector<bool> ans;
  twoSAT(int _n) : n(_n), graph(2 * _n), ans(_n) {}
  void add_edge(int i, bool x, int j, bool y) { // i=>j;
    if (!x)
      i += n;
    if (!y)
      j += n;
    graph.add_edge((i + n) % (2 * n), j);
    graph.add_edge((j + n) % (2 * n), i);
  }
  bool exe() {
    graph.init();
    rep(i, n) {
      if (graph.cmp[i] == graph.cmp[i + n])
        return false;
      else if (graph.cmp[i] > graph.cmp[i + n])
        ans[i] = true;
      else
        ans[i] = false;
    }
    return true;
  }

private:
  int n;
  SCC graph;
};

int main() {
  ll n, d;
  cin >> n >> d;
  twoSAT g(n);
  vl x(n), y(n);
  rep(i, n) cin >> x[i] >> y[i];
  rep(i, n) {
    repl(j, i + 1, n) {
      if (abs(x[i] - x[j]) < d) {
        g.add_edge(i, 0, j, 0);
      }
      if (abs(x[i] - y[j]) < d) {
        g.add_edge(i, 0, j, 1);
      }
      if (abs(y[i] - x[j]) < d) {
        g.add_edge(i, 1, j, 0);
      }
      if (abs(y[i] - y[j]) < d) {
        g.add_edge(i, 1, j, 1);
      }
    }
  }
  if (g.exe()) {
    cout << "Yes" << endl;
    rep(i, n) {
      if (g.ans[i])
        cout << x[i] << endl;
      else
        cout << y[i] << endl;
    }
  } else {
    cout << "No" << endl;
  }
}