Problem p03442 (C++)

Buggy submission (status: Runtime Error):
/* be name khoda */

// #define long_enable
#include <algorithm>
#include <cstring>
#include <fstream>
#include <iostream>
#include <map>
#include <numeric>
#include <set>
#include <vector>
using namespace std;

#ifdef long_enable
typedef long long int ll;
#else
typedef int ll;
#endif

typedef pair<ll, ll> pii;
typedef pair<pii, ll> ppi;
typedef pair<ll, pii> pip;
typedef vector<ll> vi;
typedef vector<pii> vpii;

#define forifrom(i, s, n) for (ll i = s; i < n; ++i)
#define forirto(i, n, e) for (ll i = (n)-1; i >= e; --i)
#define fori(i, n) forifrom(i, 0, n)
#define forir(i, n) forirto(i, n, 0)

#define F first
#define S second
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define smin(a, b) a = min(a, (b))
#define smax(a, b) a = max(a, (b))

#define debug(x) cout << #x << " -> " << (x) << endl
#define debug2(x, y)                                                           \
  cout << #x << ' ' << #y << " -> " << (x) << ' ' << (y) << endl
#define debug3(x, y, z)                                                        \
  cout << #x << ' ' << #y << ' ' << #z << " -> " << (x) << ' ' << (y) << ' '   \
       << (z) << endl
#define debug4(x, y, z, t)                                                     \
  cout << #x << ' ' << #y << ' ' << #z << ' ' << #t << " -> " << (x) << ' '    \
       << (y) << ' ' << (z) << ' ' << (t) << endl
#define debuga(x, n)                                                           \
  cout << #x << " -> ";                                                        \
  fori(i1_da, n) { cout << (x)[i1_da] << ' '; }                                \
  cout << endl
#define debugaa(x, n, m)                                                       \
  cout << #x << " ->\n";                                                       \
  fori(i1_daa, n) {                                                            \
    fori(i2_daa, m) { cout << (x)[i1_daa][i2_daa] << ' '; }                    \
    cout << '\n';                                                              \
  }                                                                            \
  cout << endl

const ll MOD = 1000000007;
const ll INF = 2000000000;
const long long BIG = 1446803456761533460LL;

#define XL (x << 1)
#define XR (XL | 1)
#define MD ((l + r) >> 1)
#define Add(a, b) a = ((a) + (b)) % MOD
#define Mul(a, b) a = (1LL * (a) * (b)) % MOD

// -----------------------------------------------------------------------

const ll maxn = 100010;
const ll maxa = 15;

ll n, A[maxa], B[maxn], dp[1 << maxa], val[1 << maxa], bt[1 << maxa];

int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  // ifstream cin(".in");

  cin >> n;
  fori(i, n - 1) {
    ll a, b, c;
    cin >> a >> b >> c;
    A[a] ^= c, A[b] ^= c;
  }
  fori(i, n)++ B[A[i]];
  ll cm = B[0];
  ll mask = 0;
  fori(i, maxa) {
    cm += B[i + 1] >> 1;
    if (B[i + 1] & 1)
      mask ^= 1 << i;
  }

  fori(i, maxa) bt[1 << i] = i + 1;
  forifrom(i, 1, 1 << maxa) {
    ll lb = i & -i;
    val[i] = val[i ^ lb] ^ bt[lb];
  }
  forifrom(i, 1, 1 << maxa) {
    for (ll j = i; j; j = (j - 1) & i) {
      smax(dp[i], dp[i ^ j] + (val[j] == 0));
    }
  }

  cm += dp[mask];
  cout << n - cm << '\n';
}


Fixed submission:
/* be name khoda */

// #define long_enable
#include <algorithm>
#include <cstring>
#include <fstream>
#include <iostream>
#include <map>
#include <numeric>
#include <set>
#include <vector>
using namespace std;

#ifdef long_enable
typedef long long int ll;
#else
typedef int ll;
#endif

typedef pair<ll, ll> pii;
typedef pair<pii, ll> ppi;
typedef pair<ll, pii> pip;
typedef vector<ll> vi;
typedef vector<pii> vpii;

#define forifrom(i, s, n) for (ll i = s; i < n; ++i)
#define forirto(i, n, e) for (ll i = (n)-1; i >= e; --i)
#define fori(i, n) forifrom(i, 0, n)
#define forir(i, n) forirto(i, n, 0)

#define F first
#define S second
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define smin(a, b) a = min(a, (b))
#define smax(a, b) a = max(a, (b))

#define debug(x) cout << #x << " -> " << (x) << endl
#define debug2(x, y)                                                           \
  cout << #x << ' ' << #y << " -> " << (x) << ' ' << (y) << endl
#define debug3(x, y, z)                                                        \
  cout << #x << ' ' << #y << ' ' << #z << " -> " << (x) << ' ' << (y) << ' '   \
       << (z) << endl
#define debug4(x, y, z, t)                                                     \
  cout << #x << ' ' << #y << ' ' << #z << ' ' << #t << " -> " << (x) << ' '    \
       << (y) << ' ' << (z) << ' ' << (t) << endl
#define debuga(x, n)                                                           \
  cout << #x << " -> ";                                                        \
  fori(i1_da, n) { cout << (x)[i1_da] << ' '; }                                \
  cout << endl
#define debugaa(x, n, m)                                                       \
  cout << #x << " ->\n";                                                       \
  fori(i1_daa, n) {                                                            \
    fori(i2_daa, m) { cout << (x)[i1_daa][i2_daa] << ' '; }                    \
    cout << '\n';                                                              \
  }                                                                            \
  cout << endl

const ll MOD = 1000000007;
const ll INF = 2000000000;
const long long BIG = 1446803456761533460LL;

#define XL (x << 1)
#define XR (XL | 1)
#define MD ((l + r) >> 1)
#define Add(a, b) a = ((a) + (b)) % MOD
#define Mul(a, b) a = (1LL * (a) * (b)) % MOD

// -----------------------------------------------------------------------

const ll maxn = 100010;
const ll maxa = 15;

ll n, A[maxn], B[maxa + 1], dp[1 << maxa], val[1 << maxa], bt[1 << maxa];

int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  // ifstream cin(".in");

  cin >> n;
  fori(i, n - 1) {
    ll a, b, c;
    cin >> a >> b >> c;
    A[a] ^= c, A[b] ^= c;
  }
  fori(i, n)++ B[A[i]];
  ll cm = B[0];
  ll mask = 0;
  fori(i, maxa) {
    cm += B[i + 1] >> 1;
    if (B[i + 1] & 1)
      mask ^= 1 << i;
  }

  fori(i, maxa) bt[1 << i] = i + 1;
  forifrom(i, 1, 1 << maxa) {
    ll lb = i & -i;
    val[i] = val[i ^ lb] ^ bt[lb];
  }
  forifrom(i, 1, 1 << maxa) {
    for (ll j = i; j; j = (j - 1) & i) {
      smax(dp[i], dp[i ^ j] + (val[j] == 0));
    }
  }

  cm += dp[mask];
  cout << n - cm << '\n';
}