DataStructure/segment_tree.hpp

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• Last update: 2020-07-26 22:31:04+09:00
• Include: #include "DataStructure/segment_tree.hpp"

Verified with

• Verify/hld_path.test.cpp
• Verify/hld_subtree.test.cpp
• Verify/segment_tree_affine.test.cpp
• Verify/segment_tree_rsq.test.cpp

Code

#pragma once

#include <vector>
#include <functional>

template <class T>
struct SegmentTree {
    using Merger = std::function<T(T, T)>;

    int length;
    std::vector<T> dat;
    T unit;
    Merger merge;

    SegmentTree() = default;

    SegmentTree(int n, const T& unit, const Merger& merge)
        : length(1), unit(unit), merge(merge) {
        while (length < n) length <<= 1;
        dat.assign(length * 2, unit);
    }

    template <class Container>
    SegmentTree(const Container& elems, const T& unit, const Merger& merge)
        : length(1), unit(unit), merge(merge) {
        int n = elems.size();
        while (length < n) length <<= 1;

        dat.assign(length * 2, unit);

        std::copy(elems.begin(), elems.end(), dat.begin() + length);

        for (int nidx = length - 1; nidx >= 1; --nidx) {
            T vl = dat[nidx * 2 + 0];
            T vr = dat[nidx * 2 + 1];
            dat[nidx] = merge(vl, vr);
        }
    }

    void update(int nidx, const T& elem) {
        nidx += length;
        dat[nidx] = elem;

        while (nidx > 0) {
            nidx >>= 1;
            T vl = dat[nidx * 2 + 0];
            T vr = dat[nidx * 2 + 1];
            dat[nidx] = merge(vl, vr);
        }
    }

    T fold(int ql, int qr) const {
        ql = std::max(ql, 0);
        qr = std::min(qr, length);
        ql += length, qr += length;

        T lacc = unit, racc = unit;
        while (ql < qr) {
            if (ql & 1) {
                lacc = merge(lacc, dat[ql]);
                ++ql;
            }
            if (qr & 1) {
                --qr;
                racc = merge(dat[qr], racc);
            }
            ql >>= 1, qr >>= 1;
        }

        return merge(lacc, racc);
    }

    T get(int idx) const { return dat[idx + length]; }
    T fold_all() const { return dat[1]; }
};

#line 2 "DataStructure/segment_tree.hpp"

#include <vector>
#include <functional>

template <class T>
struct SegmentTree {
    using Merger = std::function<T(T, T)>;

    int length;
    std::vector<T> dat;
    T unit;
    Merger merge;

    SegmentTree() = default;

    SegmentTree(int n, const T& unit, const Merger& merge)
        : length(1), unit(unit), merge(merge) {
        while (length < n) length <<= 1;
        dat.assign(length * 2, unit);
    }

    template <class Container>
    SegmentTree(const Container& elems, const T& unit, const Merger& merge)
        : length(1), unit(unit), merge(merge) {
        int n = elems.size();
        while (length < n) length <<= 1;

        dat.assign(length * 2, unit);

        std::copy(elems.begin(), elems.end(), dat.begin() + length);

        for (int nidx = length - 1; nidx >= 1; --nidx) {
            T vl = dat[nidx * 2 + 0];
            T vr = dat[nidx * 2 + 1];
            dat[nidx] = merge(vl, vr);
        }
    }

    void update(int nidx, const T& elem) {
        nidx += length;
        dat[nidx] = elem;

        while (nidx > 0) {
            nidx >>= 1;
            T vl = dat[nidx * 2 + 0];
            T vr = dat[nidx * 2 + 1];
            dat[nidx] = merge(vl, vr);
        }
    }

    T fold(int ql, int qr) const {
        ql = std::max(ql, 0);
        qr = std::min(qr, length);
        ql += length, qr += length;

        T lacc = unit, racc = unit;
        while (ql < qr) {
            if (ql & 1) {
                lacc = merge(lacc, dat[ql]);
                ++ql;
            }
            if (qr & 1) {
                --qr;
                racc = merge(dat[qr], racc);
            }
            ql >>= 1, qr >>= 1;
        }

        return merge(lacc, racc);
    }

    T get(int idx) const { return dat[idx + length]; }
    T fold_all() const { return dat[1]; }
};

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