Problem p02649 (C++) — buggy submission, verdict: Time Limit Exceeded

/*{{{*/
#include <algorithm>
#include <assert.h>
#include <bitset>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <limits.h>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#define SZ(X) ((int)(X).size())
#define ALL(X) (X).begin(), (X).end()
#define REP(I, N) for (int I = 0; I < (N); ++I)
#define REPP(I, A, B) for (int I = (A); I < (B); ++I)
#define FOR(I, A, B) for (int I = (A); I <= (B); ++I)
#define FORS(I, S) for (int I = 0; S[I]; ++I)
#define RS(X) scanf("%s", (X))
#define SORT_UNIQUE(c)                                                         \\
  (sort(c.begin(), c.end()),                                                   \\
   c.resize(distance(c.begin(), unique(c.begin(), c.end()))))
#define GET_POS(c, x) (lower_bound(c.begin(), c.end(), x) - c.begin())
#define CASET                                                                  \\
  int ___T;                                                                    \\
  scanf("%d", &___T);                                                          \\
  for (int cs = 1; cs <= ___T; cs++)
#define MP make_pair
#define PB emplace_back
#define MS0(X) memset((X), 0, sizeof((X)))
#define MS1(X) memset((X), -1, sizeof((X)))
#define LEN(X) strlen(X)
#define F first
#define S second
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
typedef long double LD;
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef vector<PII> VPII;
typedef pair<LL, LL> PLL;
typedef vector<PLL> VPLL;
template <class T> void _R(T &x) { cin >> x; }
void _R(int &x) { scanf("%d", &x); }
void _R(int64_t &x) { scanf("%lld", &x); }
void _R(double &x) { scanf("%lf", &x); }
void _R(char &x) { scanf(" %c", &x); }
void _R(char *x) { scanf("%s", x); }
void R() {}
template <class T, class... U> void R(T &head, U &...tail) {
  _R(head);
  R(tail...);
}
template <class T> void _W(const T &x) { cout << x; }
void _W(const int &x) { printf("%d", x); }
void _W(const int64_t &x) { printf("%lld", x); }
void _W(const double &x) { printf("%.16f", x); }
void _W(const char &x) { putchar(x); }
void _W(const char *x) { printf("%s", x); }
template <class T, class U> void _W(const pair<T, U> &x) {
  _W(x.F);
  putchar(' ');
  _W(x.S);
}
template <class T> void _W(const vector<T> &x) {
  for (auto i = x.begin(); i != x.end(); _W(*i++))
    if (i != x.cbegin())
      putchar(' ');
}
void W() {}
template <class T, class... U> void W(const T &head, const U &...tail) {
  _W(head);
  putchar(sizeof...(tail) ? ' ' : '\\n');
  W(tail...);
}
#ifdef HOME
#define DEBUG(...)                                                             \\
  {                                                                            \\
    printf("[DEBUG] ");                                                        \\
    W(__VA_ARGS__);                                                            \\
  }
#else
#define DEBUG(...)
#endif
int MOD = 1e9 + 7;
void ADD(LL &x, LL v) {
  x = (x + v) % MOD;
  if (x < 0)
    x += MOD;
}
/*}}}*/
const int SIZE = 1 << 20;
#include <unordered_map>
int N, K, s, t;
bool valid(int x) { return (x & s) == s && (x | t) == t; }
LL dp[1 << 18];
int get_bit(int x, int v) { return (x >> v) & 1; }
LL CC[66][66];
LL get(int x) {
  LL ret = 0;
  FOR(i, 1, K - 1) ret += CC[x][i];
  return ret;
}
void solve() {
  REP(i, 66) {
    CC[i][0] = 1;
    FOR(j, 1, i) CC[i][j] = CC[i - 1][j] + CC[i - 1][j - 1];
  }
  R(N, K, s, t);
  if ((s & t) != s) {
    W(0);
    return;
  }
  VI A(N);
  REP(i, N) R(A[i]);
  {
    int it = 0;
    REP(i, N) {
      if (valid(A[i]))
        A[it++] = A[i] ^ s;
    }
    A.resize(it);
    N = it;
    K = min(K, N);
    t ^= s;
  }
  LL an = 0;
  REP(i, N) {
    int base = A[i];
    MS0(dp);
    REPP(j, i + 1, N) { dp[base ^ A[j]]++; }
    REP(j, 18) {
      REP(k, 1 << 18) {
        if (get_bit(k, j))
          dp[k] += dp[k ^ (1 << j)];
      }
    }
    REP(k, 1 << 18) { dp[k] = get(dp[k]); }
    for (int j = 17; j >= 0; j--) {
      REP(k, 1 << 18) {
        if (get_bit(k, j))
          dp[k] -= dp[k ^ (1 << j)];
      }
    }
    an += dp[t];
  }
  W(an);
}
int main() {
#define MULTITEST 0
#if MULTITEST
  CASET { solve(); }
#else
  solve();
#endif
  return 0;
}


Error: TLE

Fixed submission:

/*{{{*/
#include <algorithm>
#include <assert.h>
#include <bitset>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <limits.h>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#define SZ(X) ((int)(X).size())
#define ALL(X) (X).begin(), (X).end()
#define REP(I, N) for (int I = 0; I < (N); ++I)
#define REPP(I, A, B) for (int I = (A); I < (B); ++I)
#define FOR(I, A, B) for (int I = (A); I <= (B); ++I)
#define FORS(I, S) for (int I = 0; S[I]; ++I)
#define RS(X) scanf("%s", (X))
#define SORT_UNIQUE(c)                                                         \\
  (sort(c.begin(), c.end()),                                                   \\
   c.resize(distance(c.begin(), unique(c.begin(), c.end()))))
#define GET_POS(c, x) (lower_bound(c.begin(), c.end(), x) - c.begin())
#define CASET                                                                  \\
  int ___T;                                                                    \\
  scanf("%d", &___T);                                                          \\
  for (int cs = 1; cs <= ___T; cs++)
#define MP make_pair
#define PB emplace_back
#define MS0(X) memset((X), 0, sizeof((X)))
#define MS1(X) memset((X), -1, sizeof((X)))
#define LEN(X) strlen(X)
#define F first
#define S second
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
typedef long double LD;
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef vector<PII> VPII;
typedef pair<LL, LL> PLL;
typedef vector<PLL> VPLL;
template <class T> void _R(T &x) { cin >> x; }
void _R(int &x) { scanf("%d", &x); }
void _R(int64_t &x) { scanf("%lld", &x); }
void _R(double &x) { scanf("%lf", &x); }
void _R(char &x) { scanf(" %c", &x); }
void _R(char *x) { scanf("%s", x); }
void R() {}
template <class T, class... U> void R(T &head, U &...tail) {
  _R(head);
  R(tail...);
}
template <class T> void _W(const T &x) { cout << x; }
void _W(const int &x) { printf("%d", x); }
void _W(const int64_t &x) { printf("%lld", x); }
void _W(const double &x) { printf("%.16f", x); }
void _W(const char &x) { putchar(x); }
void _W(const char *x) { printf("%s", x); }
template <class T, class U> void _W(const pair<T, U> &x) {
  _W(x.F);
  putchar(' ');
  _W(x.S);
}
template <class T> void _W(const vector<T> &x) {
  for (auto i = x.begin(); i != x.end(); _W(*i++))
    if (i != x.cbegin())
      putchar(' ');
}
void W() {}
template <class T, class... U> void W(const T &head, const U &...tail) {
  _W(head);
  putchar(sizeof...(tail) ? ' ' : '\\n');
  W(tail...);
}
#ifdef HOME
#define DEBUG(...)                                                             \\
  {                                                                            \\
    printf("[DEBUG] ");                                                        \\
    W(__VA_ARGS__);                                                            \\
  }
#else
#define DEBUG(...)
#endif
int MOD = 1e9 + 7;
void ADD(LL &x, LL v) {
  x = (x + v) % MOD;
  if (x < 0)
    x += MOD;
}
/*}}}*/
const int SIZE = 1 << 20;
#include <unordered_map>
int N, K, s, t;
bool valid(int x) { return (x & s) == s && (x | t) == t; }
LL dp[51][1 << 18];
void solve() {
  R(N, K, s, t);
  if ((s & t) != s) {
    W(0);
    return;
  }
  VI A(N);
  REP(i, N) R(A[i]);
  {
    int it = 0;
    REP(i, N) {
      if (valid(A[i]))
        A[it++] = A[i];
    }
    A.resize(it);
    N = it;
    K = min(K, N);
  }
  LL an = 0;
  REP(i, N) {
    int base = A[i];
    MS0(dp);
    dp[1][0] = 1;
    int cc = 1;
    REPP(j, i + 1, N) {
      for (int k = min(K - 1, cc); k >= 0; k--) {
        for (int y = t;; y = (y - 1) & t) {
          if (dp[k][y]) {
            dp[k + 1][y | (A[j] ^ base)] += dp[k][y];
          }
          if (!y)
            break;
        }
      }
      cc++;
    }
    FOR(j, 1, K) { an += dp[j][t ^ s]; }
  }
  W(an);
}
int main() {
#define MULTITEST 0
#if MULTITEST
  CASET { solve(); }
#else
  solve();
#endif
  return 0;
}