bit/ctz.hpp

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• Last update: 2024-11-09 00:49:07+00:00
• Include: #include "bit/ctz.hpp"

Depends on

• prelude.hpp

Required by

• bit/k_subset.hpp
• ds/doubling.hpp
• ds/dual_segtree.hpp
• ds/lazy_segtree.hpp
• ds/w_ary_tree.hpp
• mod/sqrt.hpp
• nt/factorize.hpp
• nt/gcd.hpp
• nt/totient_of.hpp
• num/interpolate.hpp
• poset/set.hpp
• poset/set_ranked.hpp
• ps/berlekamp_massey.hpp
• ps/bostan_mori.hpp
• ps/chirp_z.hpp
• ps/exp.hpp
• ps/fft.hpp
• ps/fps.hpp
• ps/frac.hpp
• ps/inv.hpp
• ps/online_fft.hpp
• ps/semi_online_fft.hpp

Verified with

• test/bit/k_subset.test.cpp
• test/ds/dual_segtree.test.cpp
• test/ds/w_ary_tree.test.cpp
• test/nt/totient_of.test.cpp
• test/poset/set.and.test.cpp
• test/poset/set.xor.test.cpp
• test/poset/set_ranked.test.cpp
• test/ps/berlekamp_massey.test.cpp
• test/ps/bostan_mori.test.cpp
• test/ps/fps.exp.test.cpp
• test/ps/fps.inv.test.cpp
• test/ps/fps.log.test.cpp
• test/ps/fps.pow.test.cpp
• test/ps/interpolate.test.cpp
• test/ps/online_fft.test.cpp
• test/ps/semi_online_fft.test.cpp

Code

#pragma once
#include "prelude.hpp"

#pragma GCC target("bmi")

template <class T>
int ctz(T x) {
  if (!x) return sizeof(T) * 8;
  if constexpr (sizeof(T) <= sizeof(unsigned)) {
    return __builtin_ctz((unsigned)x);
  } else if constexpr (sizeof(T) <= sizeof(unsigned long long)) {
    return __builtin_ctzll((unsigned long long)x);
  } else if constexpr (sizeof(T) <= sizeof(unsigned long long) * 2) {
    unsigned long long y = x;
    return y ? ctz(y)
             : sizeof(y) * 8 + ctz((unsigned long long)(x >> sizeof(y) * 8));
  }
}

#line 2 "prelude.hpp"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vector<int>>;
using vll = vector<ll>;
using vvll = vector<vector<ll>>;
using vc = vector<char>;
#define rep2(i, m, n) for (auto i = (m); i < (n); i++)
#define rep(i, n) rep2(i, 0, n)
#define repr2(i, m, n) for (auto i = (n); i-- > (m);)
#define repr(i, n) repr2(i, 0, n)
#define all(x) begin(x), end(x)
auto ndvec(int n, auto e) { return vector(n, e); }
auto ndvec(int n, auto ...e) { return vector(n, ndvec(e...)); }
auto comp_key(auto&& f) { return [&](auto&& a, auto&& b) { return f(a) < f(b); }; }
auto& max(const auto& a, const auto& b) { return a < b ? b : a; }
auto& min(const auto& a, const auto& b) { return b < a ? b : a; }
#if __cpp_lib_ranges
namespace R = std::ranges;
namespace V = std::views;
#endif
#line 3 "bit/ctz.hpp"

#pragma GCC target("bmi")

template <class T>
int ctz(T x) {
  if (!x) return sizeof(T) * 8;
  if constexpr (sizeof(T) <= sizeof(unsigned)) {
    return __builtin_ctz((unsigned)x);
  } else if constexpr (sizeof(T) <= sizeof(unsigned long long)) {
    return __builtin_ctzll((unsigned long long)x);
  } else if constexpr (sizeof(T) <= sizeof(unsigned long long) * 2) {
    unsigned long long y = x;
    return y ? ctz(y)
             : sizeof(y) * 8 + ctz((unsigned long long)(x >> sizeof(y) * 8));
  }
}

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