Tifa's CP Library

:heavy_check_mark: hash_substr (src/code/str/hash_substr.hpp)

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Code

#ifndef TIFALIBS_STR_HASH_SUBSTR
#define TIFALIBS_STR_HASH_SUBSTR

#include "../util/util.hpp"

namespace tifa_libs::str {

template <class mint, u32 base = 131>
class hash_substr {
  static inline vec<mint> p;
  vec<mint> hash;

 public:
  explicit constexpr hash_substr() {}

  constexpr void set(strnv s) {
    hash.resize(1, 0), hash.reserve(s.size() + 1);
    for (char c : s) hash.push_back(hash.back() * base + (u32)c + 1);
    if (p.size() <= s.size()) {
      if (p.empty()) p.push_back(1);
      p.reserve(s.size() + 1);
      while (p.size() <= s.size()) p.push_back(p.back() * base);
    }
  }
  constexpr u32 size() const { return u32(hash.size() - 1); }
  constexpr mint get(u32 pos, u32 len = -1_u32) const {
    assert(!p.empty() && pos < hash.size());
    return hash[pos + std::min(len, (u32)hash.size() - 1 - pos)] - hash[pos] * p[len];
  }
};

}  // namespace tifa_libs::str

#endif
#line 1 "src/code/str/hash_substr.hpp"



#line 1 "src/code/util/util.hpp"



#include <bits/stdc++.h>

template <class T>
constexpr T abs(T x) { return x < 0 ? -x : x; }

using i8 = int8_t;
using i16 = int16_t;
using i32 = int32_t;
using i64 = int64_t;
using i128 = __int128_t;
using isz = ptrdiff_t;

using u8 = uint8_t;
using u16 = uint16_t;
using u32 = uint32_t;
using u64 = uint64_t;
using u128 = __uint128_t;
using usz = size_t;

using f32 = float;
using f64 = double;
using f128 = long double;

template <class T>
using ptt = std::pair<T, T>;
template <class T>
using pt3 = std::tuple<T, T, T>;
template <class T>
using pt4 = std::tuple<T, T, T, T>;

template <class T, usz N>
using arr = std::array<T, N>;
template <class T>
using vec = std::vector<T>;
template <class T>
using vvec = vec<vec<T>>;
template <class T>
using v3ec = vec<vvec<T>>;
template <class U, class T>
using vecp = vec<std::pair<U, T>>;
template <class U, class T>
using vvecp = vvec<std::pair<U, T>>;
template <class T>
using vecpt = vec<ptt<T>>;
template <class T>
using vvecpt = vvec<ptt<T>>;

template <class T, class C = std::less<T>>
using pq = std::priority_queue<T, vec<T>, C>;
template <class T>
using pqg = std::priority_queue<T, vec<T>, std::greater<T>>;

using strn = std::string;
using strnv = std::string_view;

using vecu = vec<u32>;
using vvecu = vvec<u32>;
using v3ecu = v3ec<u32>;
using vecu64 = vec<u64>;
using vecb = vec<bool>;
using vvecb = vvec<bool>;

#ifdef ONLINE_JUDGE
#undef assert
#define assert(x) 42
#endif

using namespace std::literals;

constexpr i8 operator""_i8(unsigned long long x) { return (i8)x; }
constexpr i16 operator""_i16(unsigned long long x) { return (i16)x; }
constexpr i32 operator""_i32(unsigned long long x) { return (i32)x; }
constexpr i64 operator""_i64(unsigned long long x) { return (i64)x; }
constexpr isz operator""_iz(unsigned long long x) { return (isz)x; }

constexpr u8 operator""_u8(unsigned long long x) { return (u8)x; }
constexpr u16 operator""_u16(unsigned long long x) { return (u16)x; }
constexpr u32 operator""_u32(unsigned long long x) { return (u32)x; }
constexpr u64 operator""_u64(unsigned long long x) { return (u64)x; }
constexpr usz operator""_uz(unsigned long long x) { return (usz)x; }

inline const auto fn_0 = [](auto&&...) {};
inline const auto fn_is0 = [](auto x) { return x == 0; };


#line 5 "src/code/str/hash_substr.hpp"

namespace tifa_libs::str {

template <class mint, u32 base = 131>
class hash_substr {
  static inline vec<mint> p;
  vec<mint> hash;

 public:
  explicit constexpr hash_substr() {}

  constexpr void set(strnv s) {
    hash.resize(1, 0), hash.reserve(s.size() + 1);
    for (char c : s) hash.push_back(hash.back() * base + (u32)c + 1);
    if (p.size() <= s.size()) {
      if (p.empty()) p.push_back(1);
      p.reserve(s.size() + 1);
      while (p.size() <= s.size()) p.push_back(p.back() * base);
    }
  }
  constexpr u32 size() const { return u32(hash.size() - 1); }
  constexpr mint get(u32 pos, u32 len = -1_u32) const {
    assert(!p.empty() && pos < hash.size());
    return hash[pos + std::min(len, (u32)hash.size() - 1 - pos)] - hash[pos] * p[len];
  }
};

}  // namespace tifa_libs::str


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