cp-library-cpp
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Fenwick Tree Set
(library/datastructure/fenwick_tree/fenwick_tree_set.hpp)
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- Last update: 2026-06-19 20:35:33+09:00
- Include:
#include "library/datastructure/fenwick_tree/fenwick_tree_set.hpp"
Fenwick Tree Set
Required by
Factorial Number
(library/number/factorial_number.hpp)
- Range Set Range Composite
(library/range_query/range_set_range_composite.hpp)
Verified with
Code
#ifndef SUISEN_FENWICK_TREE_SET
#define SUISEN_FENWICK_TREE_SET
#include <array>
#include <cassert>
#include <cstdint>
#include <numeric>
#include <vector>
#ifdef _MSC_VER
# include <intrin.h>
#else
# include <x86intrin.h>
#endif
namespace suisen {
struct fenwick_tree_set {
private:
template <typename T>
struct is_container {
template <typename T2>
static auto test(T2 t) -> decltype(++t.begin() != t.end(), *t.begin(), std::true_type{});
static std::false_type test(...);
public:
static constexpr bool value = decltype(test(std::declval<T>()))::value;
};
static constexpr int WORD = 64, MASK_WORD = 63, LOG_WORD = 6;
static constexpr int SEARCH_WIDTH = 1;
public:
fenwick_tree_set() : fenwick_tree_set(0) {}
// Construct (an empty / a full) set and set the universe as {0,1,...,n-1}
explicit fenwick_tree_set(int n, bool full_set = false): _n(n), _wn(std::max((_n + (WORD - 1)) >> LOG_WORD, 1)), _lg(top_setbit(_wn)), _size(0), _d(_wn + 1), _bs(_wn) {
if (full_set) {
std::vector<int> values(n);
std::iota(values.begin(), values.end(), 0);
construct_from_values(values);
}
}
// Construct a set containing the values in `values`.
template <typename Container, std::enable_if_t<is_container<Container>::value, std::nullptr_t> = nullptr>
fenwick_tree_set(int n, const Container &values): fenwick_tree_set(n) {
construct_from_values(values);
}
// Construct a set containing the values `i` such that `seq01[i] == 1` (or `one` you give).
template <typename Container, std::enable_if_t<is_container<Container>::value, std::nullptr_t> = nullptr>
fenwick_tree_set(const Container &seq01, typename Container::value_type one = 1): fenwick_tree_set(seq01.size()) {
std::vector<int> values;
for (int i = 0; i < _n; ++i) if (seq01[i] == one) values.push_back(i);
construct_from_values(values);
}
// O(1).
// Number of elements.
int size() const { return _size; }
// O(1).
// Check if `v` is contained. `v` may be out of range.
bool contains(int v) const {
if (not (0 <= v and v < _n)) return false;
const auto [t, u] = index(v);
return (_bs[t] >> u) & 1;
}
// O(log n) if `v` is not a member, O(1) otherwise.
// Insert `v` if not contained. Raise an assertion error if `v` is out of range.
// Return `true` if `v` is inserted, `false` otherwise.
bool insert(int v) {
if (contains(v)) return false;
add<+1>(v);
const auto [t, u] = index(v);
_bs[t] |= uint64_t(1) << u;
return true;
}
// O(log n) if `v` is a member, O(1) otherwise.
// Erase `v` if contained. Raise an assertion error if `v` is out of range.
// Return `true` if `v` is erased, `false` otherwise.
bool erase(int v) {
if (not contains(v)) return false;
add<-1>(v);
const auto [t, u] = index(v);
_bs[t] &= ~(uint64_t(1) << u);
return true;
}
// O(log n).
// Count elements < `v`. `v` may be out of range.
int count_lt(int v) const {
if (v <= 0) return 0;
if (v >= _n) return _size;
auto [t, u] = index(v);
int res = __builtin_popcountll(_bs[t] & ((uint64_t(1) << u) - 1));
for (; t; t &= t - 1) res += _d[t];
return res;
}
// O(log n).
// Count elements <= `v`. `v` may be out of range.
int count_leq(int v) const { return count_lt(v + 1); }
// O(log n).
// Count elements > `v`. `v` may be out of range.
int count_gt(int v) const { return _size - count_leq(v); }
// O(log n).
// Count elements >= `v`. `v` may be out of range.
int count_geq(int v) const { return _size - count_lt(v); }
// O(log n).
// `k`-th smallest element or `-1` if `k` is out of range.
int kth_element(int k) const {
// Out of range
if (not (0 <= k and k < _size)) return -1;
// Binary search
int t = 1 << _lg;
// (I) non-leaf node
// [ t ]
// [t-p] [t+p]
for (int p = 1 << _lg >> 1; p; p >>= 1) {
if (int nk = t <= _wn ? k - _d[t] : -1; nk >= 0) k = nk, t += p;
else t -= p;
}
// (II) leaf node
if (int nk = t <= _wn ? k - _d[t] : -1; nk >= 0) k = nk, ++t;
--t;
return (t << LOG_WORD) | kth_setbit(_bs[t], k);
}
// O(log n).
// `k`-th smallest element or `-1` if `k` is out of range.
int operator[](int k) const { return kth_element(k); }
// O(log n).
// Max element <= `v` or `-1` if not exists
int max_leq(int v) const {
if (v < 0) return -1;
v = std::min(v, _n - 1);
const auto [t, u] = index(v);
const int lz = (WORD - 1) - u;
if (const uint64_t bits = _bs[t] << lz >> lz) {
return (t << LOG_WORD) | top_setbit(bits);
}
for (int i = 1; i <= SEARCH_WIDTH; ++i) {
if (t - i < 0) return -1;
if (_bs[t - i]) return ((t - i) << LOG_WORD) | top_setbit(_bs[t - i]);
}
return *--upper_bound(v);
}
// O(log n).
// Max element < `v` or `-1` if not exists
int max_lt(int v) const { return max_leq(v - 1); }
// O(log n).
// Min element >= `v` or `-1` if not exists
int min_geq(int v) const {
if (v >= _n) return -1;
v = std::max(v, 0);
const auto [t, u] = index(v);
if (const uint64_t bits = _bs[t] >> u << u) {
return (t << LOG_WORD) | __builtin_ctzll(bits);
}
for (int i = 1; i <= SEARCH_WIDTH; ++i) {
if (t + i >= _wn) return -1;
if (_bs[t + i]) return ((t + i) << LOG_WORD) | __builtin_ctzll(_bs[t + i]);
}
return *lower_bound(v);
}
// O(log n).
// Min element > `v` or `-1` if not exists
int min_gt(int v) const { return min_geq(v + 1); }
private:
struct IndexHolder {
friend fenwick_tree_set;
using difference_type = int;
using value_type = int;
using pointer = value_type*;
using reference = value_type&;
using iterator_category = std::random_access_iterator_tag;
// O(1). Index of the element pointed to by the iterator. Negative values or values greater than or equal to `n` (= size of the set) means that the iterator doesn't point to any element.
int index() const { return i; }
// O(1). Check if the iterator points to some element.
bool has_value() const { return 0 <= i and i < ptr->size(); }
// O(1)
IndexHolder& operator++() { return ++i, *this; }
// O(1)
IndexHolder operator++(int) { IndexHolder ret = *this; ++(*this); return ret; }
// O(1)
IndexHolder& operator--() { return --i, *this; }
// O(1)
IndexHolder operator--(int) { IndexHolder ret = *this; --(*this); return ret; }
// O(1)
IndexHolder& operator+=(difference_type dif) { return i += dif, *this; }
// O(1)
friend IndexHolder operator+(IndexHolder it, difference_type dif) { it += dif; return it; }
// O(1)
friend IndexHolder operator+(difference_type dif, IndexHolder it) { it += dif; return it; }
// O(1)
IndexHolder& operator-=(difference_type dif) { return i -= dif, *this; }
// O(1)
friend IndexHolder operator-(IndexHolder it, difference_type dif) { it -= dif; return it; }
// O(1)
difference_type operator-(const IndexHolder &rhs) const { return i - rhs.i; }
// O(log n)
value_type operator[](difference_type i) const { return *((*this) + i); }
// O(log n)
value_type operator*() const { return ptr->kth_element(i); }
// O(1)
bool operator!=(const IndexHolder &rhs) const { return i != rhs.i; }
// O(1)
bool operator==(const IndexHolder &rhs) const { return i == rhs.i; }
// O(1)
bool operator<(const IndexHolder &rhs) const { return i < rhs.i; }
// O(1)
bool operator<=(const IndexHolder &rhs) const { return i <= rhs.i; }
// O(1)
bool operator>(const IndexHolder &rhs) const { return i > rhs.i; }
// O(1)
bool operator>=(const IndexHolder &rhs) const { return i >= rhs.i; }
private:
IndexHolder(const fenwick_tree_set* ptr, int i) : ptr(ptr), i(i) {}
const fenwick_tree_set* ptr;
int i;
};
public:
using iterator = IndexHolder;
using difference_type = iterator::difference_type;
using value_type = iterator::value_type;
using pointer = iterator::pointer;
using reference = iterator::reference;
// O(1).
iterator begin() const { return iterator(this, 0); }
// O(1).
iterator end() const { return iterator(this, _size); }
// O(log n).
iterator lower_bound(int v) const { return iterator(this, count_lt(v)); }
// O(log n).
iterator upper_bound(int v) const { return iterator(this, count_leq(v)); }
// O(log n) if `v` is a member, O(1) otherwise.
iterator find(int v) const { return contains(v) ? lower_bound(v) : end(); }
// O(log n).
iterator erase(iterator it) { return erase(*it), it; }
private:
int _n, _wn, _lg, _size;
std::vector<int> _d; // Fenwick Tree
std::vector<uint64_t> _bs; // Bitset
template <typename Container, std::enable_if_t<is_container<Container>::value, std::nullptr_t> = nullptr>
void construct_from_values(const Container &values) {
for (int v : values) {
assert(0 <= v and v < _n);
const auto [t, u] = index(v);
if ((_bs[t] >> u) & 1) continue;
++_size;
++_d[t + 1];
_bs[t] |= uint64_t(1) << u;
}
for (int i = 1; i <= _wn; ++i) {
const int p = i + (-i & i);
if (p <= _wn) _d[p] += _d[i];
}
}
static constexpr int _large(int i) { return i >> LOG_WORD; }
static constexpr int _small(int i) { return i & MASK_WORD; }
static constexpr std::array<int, 2> index(int i) { return { _large(i), _small(i) }; }
// Position of highest set bit
static constexpr int top_setbit(uint64_t x) { return (WORD - 1) - __builtin_clzll(x); }
// Position of k-th set bit
__attribute__((target("bmi2")))
static int kth_setbit(uint64_t x, int k) { return __builtin_ctzll(_pdep_u64(uint64_t(1) << k, x)); }
template <int k>
void add(int v) {
assert(0 <= v and v < _n);
_size += k;
for (int t = _large(v) + 1; t <= _wn; t += -t & t) _d[t] += k;
}
};
} // namespace suisen
#endif // SUISEN_FENWICK_TREE_SET#line 1 "library/datastructure/fenwick_tree/fenwick_tree_set.hpp"
#include <array>
#include <cassert>
#include <cstdint>
#include <numeric>
#include <vector>
#ifdef _MSC_VER
# include <intrin.h>
#else
# include <x86intrin.h>
#endif
namespace suisen {
struct fenwick_tree_set {
private:
template <typename T>
struct is_container {
template <typename T2>
static auto test(T2 t) -> decltype(++t.begin() != t.end(), *t.begin(), std::true_type{});
static std::false_type test(...);
public:
static constexpr bool value = decltype(test(std::declval<T>()))::value;
};
static constexpr int WORD = 64, MASK_WORD = 63, LOG_WORD = 6;
static constexpr int SEARCH_WIDTH = 1;
public:
fenwick_tree_set() : fenwick_tree_set(0) {}
// Construct (an empty / a full) set and set the universe as {0,1,...,n-1}
explicit fenwick_tree_set(int n, bool full_set = false): _n(n), _wn(std::max((_n + (WORD - 1)) >> LOG_WORD, 1)), _lg(top_setbit(_wn)), _size(0), _d(_wn + 1), _bs(_wn) {
if (full_set) {
std::vector<int> values(n);
std::iota(values.begin(), values.end(), 0);
construct_from_values(values);
}
}
// Construct a set containing the values in `values`.
template <typename Container, std::enable_if_t<is_container<Container>::value, std::nullptr_t> = nullptr>
fenwick_tree_set(int n, const Container &values): fenwick_tree_set(n) {
construct_from_values(values);
}
// Construct a set containing the values `i` such that `seq01[i] == 1` (or `one` you give).
template <typename Container, std::enable_if_t<is_container<Container>::value, std::nullptr_t> = nullptr>
fenwick_tree_set(const Container &seq01, typename Container::value_type one = 1): fenwick_tree_set(seq01.size()) {
std::vector<int> values;
for (int i = 0; i < _n; ++i) if (seq01[i] == one) values.push_back(i);
construct_from_values(values);
}
// O(1).
// Number of elements.
int size() const { return _size; }
// O(1).
// Check if `v` is contained. `v` may be out of range.
bool contains(int v) const {
if (not (0 <= v and v < _n)) return false;
const auto [t, u] = index(v);
return (_bs[t] >> u) & 1;
}
// O(log n) if `v` is not a member, O(1) otherwise.
// Insert `v` if not contained. Raise an assertion error if `v` is out of range.
// Return `true` if `v` is inserted, `false` otherwise.
bool insert(int v) {
if (contains(v)) return false;
add<+1>(v);
const auto [t, u] = index(v);
_bs[t] |= uint64_t(1) << u;
return true;
}
// O(log n) if `v` is a member, O(1) otherwise.
// Erase `v` if contained. Raise an assertion error if `v` is out of range.
// Return `true` if `v` is erased, `false` otherwise.
bool erase(int v) {
if (not contains(v)) return false;
add<-1>(v);
const auto [t, u] = index(v);
_bs[t] &= ~(uint64_t(1) << u);
return true;
}
// O(log n).
// Count elements < `v`. `v` may be out of range.
int count_lt(int v) const {
if (v <= 0) return 0;
if (v >= _n) return _size;
auto [t, u] = index(v);
int res = __builtin_popcountll(_bs[t] & ((uint64_t(1) << u) - 1));
for (; t; t &= t - 1) res += _d[t];
return res;
}
// O(log n).
// Count elements <= `v`. `v` may be out of range.
int count_leq(int v) const { return count_lt(v + 1); }
// O(log n).
// Count elements > `v`. `v` may be out of range.
int count_gt(int v) const { return _size - count_leq(v); }
// O(log n).
// Count elements >= `v`. `v` may be out of range.
int count_geq(int v) const { return _size - count_lt(v); }
// O(log n).
// `k`-th smallest element or `-1` if `k` is out of range.
int kth_element(int k) const {
// Out of range
if (not (0 <= k and k < _size)) return -1;
// Binary search
int t = 1 << _lg;
// (I) non-leaf node
// [ t ]
// [t-p] [t+p]
for (int p = 1 << _lg >> 1; p; p >>= 1) {
if (int nk = t <= _wn ? k - _d[t] : -1; nk >= 0) k = nk, t += p;
else t -= p;
}
// (II) leaf node
if (int nk = t <= _wn ? k - _d[t] : -1; nk >= 0) k = nk, ++t;
--t;
return (t << LOG_WORD) | kth_setbit(_bs[t], k);
}
// O(log n).
// `k`-th smallest element or `-1` if `k` is out of range.
int operator[](int k) const { return kth_element(k); }
// O(log n).
// Max element <= `v` or `-1` if not exists
int max_leq(int v) const {
if (v < 0) return -1;
v = std::min(v, _n - 1);
const auto [t, u] = index(v);
const int lz = (WORD - 1) - u;
if (const uint64_t bits = _bs[t] << lz >> lz) {
return (t << LOG_WORD) | top_setbit(bits);
}
for (int i = 1; i <= SEARCH_WIDTH; ++i) {
if (t - i < 0) return -1;
if (_bs[t - i]) return ((t - i) << LOG_WORD) | top_setbit(_bs[t - i]);
}
return *--upper_bound(v);
}
// O(log n).
// Max element < `v` or `-1` if not exists
int max_lt(int v) const { return max_leq(v - 1); }
// O(log n).
// Min element >= `v` or `-1` if not exists
int min_geq(int v) const {
if (v >= _n) return -1;
v = std::max(v, 0);
const auto [t, u] = index(v);
if (const uint64_t bits = _bs[t] >> u << u) {
return (t << LOG_WORD) | __builtin_ctzll(bits);
}
for (int i = 1; i <= SEARCH_WIDTH; ++i) {
if (t + i >= _wn) return -1;
if (_bs[t + i]) return ((t + i) << LOG_WORD) | __builtin_ctzll(_bs[t + i]);
}
return *lower_bound(v);
}
// O(log n).
// Min element > `v` or `-1` if not exists
int min_gt(int v) const { return min_geq(v + 1); }
private:
struct IndexHolder {
friend fenwick_tree_set;
using difference_type = int;
using value_type = int;
using pointer = value_type*;
using reference = value_type&;
using iterator_category = std::random_access_iterator_tag;
// O(1). Index of the element pointed to by the iterator. Negative values or values greater than or equal to `n` (= size of the set) means that the iterator doesn't point to any element.
int index() const { return i; }
// O(1). Check if the iterator points to some element.
bool has_value() const { return 0 <= i and i < ptr->size(); }
// O(1)
IndexHolder& operator++() { return ++i, *this; }
// O(1)
IndexHolder operator++(int) { IndexHolder ret = *this; ++(*this); return ret; }
// O(1)
IndexHolder& operator--() { return --i, *this; }
// O(1)
IndexHolder operator--(int) { IndexHolder ret = *this; --(*this); return ret; }
// O(1)
IndexHolder& operator+=(difference_type dif) { return i += dif, *this; }
// O(1)
friend IndexHolder operator+(IndexHolder it, difference_type dif) { it += dif; return it; }
// O(1)
friend IndexHolder operator+(difference_type dif, IndexHolder it) { it += dif; return it; }
// O(1)
IndexHolder& operator-=(difference_type dif) { return i -= dif, *this; }
// O(1)
friend IndexHolder operator-(IndexHolder it, difference_type dif) { it -= dif; return it; }
// O(1)
difference_type operator-(const IndexHolder &rhs) const { return i - rhs.i; }
// O(log n)
value_type operator[](difference_type i) const { return *((*this) + i); }
// O(log n)
value_type operator*() const { return ptr->kth_element(i); }
// O(1)
bool operator!=(const IndexHolder &rhs) const { return i != rhs.i; }
// O(1)
bool operator==(const IndexHolder &rhs) const { return i == rhs.i; }
// O(1)
bool operator<(const IndexHolder &rhs) const { return i < rhs.i; }
// O(1)
bool operator<=(const IndexHolder &rhs) const { return i <= rhs.i; }
// O(1)
bool operator>(const IndexHolder &rhs) const { return i > rhs.i; }
// O(1)
bool operator>=(const IndexHolder &rhs) const { return i >= rhs.i; }
private:
IndexHolder(const fenwick_tree_set* ptr, int i) : ptr(ptr), i(i) {}
const fenwick_tree_set* ptr;
int i;
};
public:
using iterator = IndexHolder;
using difference_type = iterator::difference_type;
using value_type = iterator::value_type;
using pointer = iterator::pointer;
using reference = iterator::reference;
// O(1).
iterator begin() const { return iterator(this, 0); }
// O(1).
iterator end() const { return iterator(this, _size); }
// O(log n).
iterator lower_bound(int v) const { return iterator(this, count_lt(v)); }
// O(log n).
iterator upper_bound(int v) const { return iterator(this, count_leq(v)); }
// O(log n) if `v` is a member, O(1) otherwise.
iterator find(int v) const { return contains(v) ? lower_bound(v) : end(); }
// O(log n).
iterator erase(iterator it) { return erase(*it), it; }
private:
int _n, _wn, _lg, _size;
std::vector<int> _d; // Fenwick Tree
std::vector<uint64_t> _bs; // Bitset
template <typename Container, std::enable_if_t<is_container<Container>::value, std::nullptr_t> = nullptr>
void construct_from_values(const Container &values) {
for (int v : values) {
assert(0 <= v and v < _n);
const auto [t, u] = index(v);
if ((_bs[t] >> u) & 1) continue;
++_size;
++_d[t + 1];
_bs[t] |= uint64_t(1) << u;
}
for (int i = 1; i <= _wn; ++i) {
const int p = i + (-i & i);
if (p <= _wn) _d[p] += _d[i];
}
}
static constexpr int _large(int i) { return i >> LOG_WORD; }
static constexpr int _small(int i) { return i & MASK_WORD; }
static constexpr std::array<int, 2> index(int i) { return { _large(i), _small(i) }; }
// Position of highest set bit
static constexpr int top_setbit(uint64_t x) { return (WORD - 1) - __builtin_clzll(x); }
// Position of k-th set bit
__attribute__((target("bmi2")))
static int kth_setbit(uint64_t x, int k) { return __builtin_ctzll(_pdep_u64(uint64_t(1) << k, x)); }
template <int k>
void add(int v) {
assert(0 <= v and v < _n);
_size += k;
for (int t = _large(v) + 1; t <= _wn; t += -t & t) _d[t] += k;
}
};
} // namespace suisen