library/data-structure/fenwick.hpp

• View this file on GitHub
• Last update: 2023-07-11 10:41:16+08:00
• Include: #include "library/data-structure/fenwick.hpp"

Required by

• library/data-structure/offline-rectangle-sum.hpp
• library/data-structure/range-add-range-sum.hpp

Verified with

• test/data-structure/fenwick/aoj-dsl-Range-Add-Query.test.cpp
• test/data-structure/fenwick/aoj-dsl-Range-Sum-Query.test.cpp
• test/data-structure/fenwick/aoj-dsl-The-Maximum-Number-of-Customers.test.cpp
• test/data-structure/fenwick/yosupo-Point-Add-Range-Sum.test.cpp
• test/data-structure/offline-rectangle-sum/yosupo-Point-Add-Rectangle-Sum.test.cpp
• test/tree/hld/aoj-grl-Range-Query-on-a-Tree.test.cpp
• test/tree/hld/yosupo-Vertex-Add-Path-Sum.test.cpp
• test/tree/hld/yosupo-Vertex-Add-Subtree-Sum.test.cpp

Code

#pragma once
#include <vector>
#include <cassert>

namespace felix {

template<class S>
struct fenwick {
public:
	fenwick() : n(0) {}
	explicit fenwick(int _n) : n(_n), data(_n) {}

	void add(int p, S x) {
		for(int i = p + 1; i <= n; i += i & -i) {
			data[i - 1] += x;
		}
	}

	// [0, p)
	S get(int p) const {
		auto ans = S();
		for(int i = p; i > 0; i -= i & -i) {
			ans += data[i - 1];
		}
		return ans;
	}

	// [l, r)
	S sum(int l, int r) const { return get(r) - get(l); }

	// 0-based
	int kth(S k) const {
		int x = 0;
		for(int i = 1 << std::__lg(n); i > 0; i >>= 1) {
			if (x + i <= n && k >= data[x + i - 1]) {
				x += i;
				k -= data[x - 1];
			}
		}
		return x;
	}

private:
	int n;
	std::vector<S> data;
};

} // namespace felix

#line 2 "library/data-structure/fenwick.hpp"
#include <vector>
#include <cassert>

namespace felix {

template<class S>
struct fenwick {
public:
	fenwick() : n(0) {}
	explicit fenwick(int _n) : n(_n), data(_n) {}

	void add(int p, S x) {
		for(int i = p + 1; i <= n; i += i & -i) {
			data[i - 1] += x;
		}
	}

	// [0, p)
	S get(int p) const {
		auto ans = S();
		for(int i = p; i > 0; i -= i & -i) {
			ans += data[i - 1];
		}
		return ans;
	}

	// [l, r)
	S sum(int l, int r) const { return get(r) - get(l); }

	// 0-based
	int kth(S k) const {
		int x = 0;
		for(int i = 1 << std::__lg(n); i > 0; i >>= 1) {
			if (x + i <= n && k >= data[x + i - 1]) {
				x += i;
				k -= data[x - 1];
			}
		}
		return x;
	}

private:
	int n;
	std::vector<S> data;
};

} // namespace felix

Back to top page