Hash cu pointeri

typedef struct element {
  int val, freq;
  element *next;
} *lista;

const int MASK = (1 << 23) - 1;
const int mod = 196613;
bitset<MASK + 1> filter;
lista h[mod];

void Insert(int x) {
  filter[x & MASK] = true;
  int key = x % mod;
  lista p;
  for (p = h[key]; p; p = p->next)
    if (p->val == x) {
      ++p->freq;
      return;
    }
  p = new element;
  p->val = x;
  p->freq = 1;
  p->next = h[key];
  h[key] = p;
}

void Erase(int x) {
  if (!filter[x & MASK])
    return;
  int key = x % mod;
  for (lista p = h[key]; p; p = p->next)
    if (p->val == x) {
      --p->freq;
      return;
    }
}

int Find(int x) {
  if (!filter[x & MASK])
    return 0;
  int key = x % mod;
  for (lista p = h[key]; p; p = p->next)
    if (p->val == x)
      return p->freq;
  return 0;
}