Problem p03690 (C++)

Buggy submission (status: Runtime Error):
#include "bits/stdc++.h"

#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fr(x) freopen(x, "r", stdin)
#define fw(x) freopen(x, "w", stdout)
#define iout(x) printf("%d\n", x)
#define lout(x) printf("%lld\n", x)
#define REP(x, l, u) for (int x = (l); x <= (u); x++)
#define RREP(x, l, u) for (int x = (l); x >= (u); x--)
#define mst(x, a) memset(x, a, sizeof(x))
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define MP make_pair
#define se second
#define fi first
#define dbg(x) cout << #x << " = " << (x) << endl;
#define sz(x) ((int)x.size())
#define cl(x) x.clear()

typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ld;
using namespace std;

const int maxn = 200010;
const int mod = 1e9 + 7;
const int MAX = 1000000010;
const double eps = 1e-6;
const double PI = acos(-1);

template <typename T> inline void read(T &x) {
  x = 0;
  T f = 1;
  char ch;
  do {
    ch = getchar();
    if (ch == '-')
      f = -1;
  } while (ch < '0' || ch > '9');
  do
    x = x * 10 + ch - '0', ch = getchar();
  while (ch <= '9' && ch >= '0');
  x *= f;
}

template <typename A, typename B> inline void read(A &x, B &y) {
  read(x);
  read(y);
}
template <typename A, typename B, typename C>
inline void read(A &x, B &y, C &z) {
  read(x);
  read(y);
  read(z);
}
template <typename A, typename B, typename C, typename D>
inline void read(A &x, B &y, C &z, D &w) {
  read(x);
  read(y);
  read(z);
  read(w);
}
template <typename A, typename B> inline A fexp(A x, B p) {
  A ans = 1;
  for (; p; p >>= 1, x = 1LL * x * x % mod)
    if (p & 1)
      ans = 1LL * ans * x % mod;
  return ans;
}
template <typename A, typename B> inline A fexp(A x, B p, A mo) {
  A ans = 1;
  for (; p; p >>= 1, x = 1LL * x * x % mo)
    if (p & 1)
      ans = 1LL * ans * x % mo;
  return ans;
}

int n, cnt, ans;

int A[maxn], B[maxn], C[maxn], D[maxn], E[maxn], fa[maxn];

int find(int i) { return fa[i] == i ? i : fa[i] = find(fa[i]); }

void Work() {
  sort(C + 1, C + n + 2);
  sort(D + 1, D + n + 2);
  REP(i, 1, n + 1) if (C[i] != D[i]) {
    puts("-1");
    exit(0);
  }
  bool ok = 1;
  REP(i, 1, n) if (A[i] != B[i]) ok = 0;
  if (ok) {
    puts("0");
    return;
  }
  REP(i, 1, n) if (A[i] != B[i]) {
    ans++;
    if (!E[A[i]])
      E[A[i]] = ++cnt;
    if (!E[B[i]])
      E[B[i]] = ++cnt;
  }
  if (!E[A[n + 1]])
    E[A[n + 1]] = ++cnt;
  if (!E[B[n + 1]])
    E[B[n + 1]] = ++cnt;
  REP(i, 1, cnt) fa[i] = i;
  REP(i, 1, n) if (A[i] != B[i]) fa[find(E[A[i]])] = find(E[B[i]]);
  REP(i, 1, cnt) if (find(i) == i) ans++;
  iout(ans - 1);
}

void Init() {
  read(n);
  REP(i, 1, n) read(A[i]);
  REP(i, 1, n) read(B[i]);
  REP(i, 1, n) A[n + 1] ^= A[i], B[n + 1] ^= B[i];
  REP(i, 1, n + 1) C[i] = A[i], D[i] = B[i];
}

int main() {
  Init();
  Work();
  return 0;
}


Fixed submission:
#include "bits/stdc++.h"

#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fr(x) freopen(x, "r", stdin)
#define fw(x) freopen(x, "w", stdout)
#define iout(x) printf("%d\n", x)
#define lout(x) printf("%lld\n", x)
#define REP(x, l, u) for (int x = (l); x <= (u); x++)
#define RREP(x, l, u) for (int x = (l); x >= (u); x--)
#define mst(x, a) memset(x, a, sizeof(x))
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define MP make_pair
#define se second
#define fi first
#define dbg(x) cout << #x << " = " << (x) << endl;
#define sz(x) ((int)x.size())
#define cl(x) x.clear()

typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ld;
using namespace std;

const int maxn = 200010;
const int mod = 1e9 + 7;
const int MAX = 1000000010;
const double eps = 1e-6;
const double PI = acos(-1);

template <typename T> inline void read(T &x) {
  x = 0;
  T f = 1;
  char ch;
  do {
    ch = getchar();
    if (ch == '-')
      f = -1;
  } while (ch < '0' || ch > '9');
  do
    x = x * 10 + ch - '0', ch = getchar();
  while (ch <= '9' && ch >= '0');
  x *= f;
}

template <typename A, typename B> inline void read(A &x, B &y) {
  read(x);
  read(y);
}
template <typename A, typename B, typename C>
inline void read(A &x, B &y, C &z) {
  read(x);
  read(y);
  read(z);
}
template <typename A, typename B, typename C, typename D>
inline void read(A &x, B &y, C &z, D &w) {
  read(x);
  read(y);
  read(z);
  read(w);
}
template <typename A, typename B> inline A fexp(A x, B p) {
  A ans = 1;
  for (; p; p >>= 1, x = 1LL * x * x % mod)
    if (p & 1)
      ans = 1LL * ans * x % mod;
  return ans;
}
template <typename A, typename B> inline A fexp(A x, B p, A mo) {
  A ans = 1;
  for (; p; p >>= 1, x = 1LL * x * x % mo)
    if (p & 1)
      ans = 1LL * ans * x % mo;
  return ans;
}

int n, cnt, ans;

int A[maxn], B[maxn], C[maxn], D[maxn], fa[maxn];

map<int, int> E;

int find(int i) { return fa[i] == i ? i : fa[i] = find(fa[i]); }

void Work() {
  sort(C + 1, C + n + 2);
  sort(D + 1, D + n + 2);
  REP(i, 1, n + 1) if (C[i] != D[i]) {
    puts("-1");
    exit(0);
  }
  bool ok = 1;
  REP(i, 1, n) if (A[i] != B[i]) ok = 0;
  if (ok) {
    puts("0");
    return;
  }
  REP(i, 1, n) if (A[i] != B[i]) {
    ans++;
    if (!E[A[i]])
      E[A[i]] = ++cnt;
    if (!E[B[i]])
      E[B[i]] = ++cnt;
  }
  if (!E[A[n + 1]])
    E[A[n + 1]] = ++cnt;
  if (!E[B[n + 1]])
    E[B[n + 1]] = ++cnt;
  REP(i, 1, cnt) fa[i] = i;
  REP(i, 1, n) if (A[i] != B[i]) fa[find(E[A[i]])] = find(E[B[i]]);
  REP(i, 1, cnt) if (find(i) == i) ans++;
  iout(ans - 1);
}

void Init() {
  read(n);
  REP(i, 1, n) read(A[i]);
  REP(i, 1, n) read(B[i]);
  REP(i, 1, n) A[n + 1] ^= A[i], B[n + 1] ^= B[i];
  REP(i, 1, n + 1) C[i] = A[i], D[i] = B[i];
}

int main() {
  Init();
  Work();
  return 0;
}