library/segtree/LazySegmentTree.hpp

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• Last update: 2025-11-24 18:49:07+09:00
• Include: #include "library/segtree/LazySegmentTree.hpp"

Depends on

• build/pch/stdc++.hpp

Required by

• library/tree/TreeLazy.hpp

Verified with

• test/AOJ/DSL_2_F.test.cpp
• test/AOJ/DSL_2_G.test.cpp
• test/AOJ/DSL_2_H.test.cpp
• test/AOJ/DSL_2_I.test.cpp
• test/AOJ/GRL_5_E.test.cpp
• test/library-checker/DataStructure/RangeAffineRangeSum.test.cpp

Code

#pragma once

template <typename Lazy> class LazySegmentTree {
    using MX = typename Lazy::MX;
    using MF = typename Lazy::MF;
    using X = typename MX::value_type;
    using F = typename MF::value_type;
    int n, log, size;
    std::vector<X> dat;
    std::vector<F> laz;

    X reflect(int k) {
        if (k < size)
            return Lazy::mapping(laz[k], dat[k]);
        return dat[k];
    }
    void point_apply(int k, const F &f) {
        if (k < size)
            MF::Lchop(f, laz[k]);
        else
            dat[k] = Lazy::mapping(f, dat[k]);
    }
    void push(int k) {
        dat[k] = reflect(k);
        point_apply(2 * k, laz[k]);
        point_apply(2 * k + 1, laz[k]);
        laz[k] = MF::unit();
    }
    void thrust(int k) {
        for (int i = log; i; i--)
            push(k >> i);
    }
    void update(int i) { dat[i] = MX::op(reflect(2 * i), reflect(2 * i + 1)); }
    void recalc(int k) {
        while (k >>= 1)
            update(k);
    }

  public:
    LazySegmentTree() : LazySegmentTree(0) {}
    LazySegmentTree(int n) : LazySegmentTree(std::vector<X>(n, MX::unit())) {}
    LazySegmentTree(const std::vector<X> &v) : n(v.size()) {
        for (log = 1; (1 << log) < n; log++) {
        }
        size = 1 << log;
        dat.assign(size << 1, MX::unit());
        laz.assign(size, MF::unit());
        for (int i = 0; i < n; ++i)
            dat[size + i] = v[i];
        for (int i = size - 1; i >= 1; --i)
            update(i);
    }

    void set(int p, X x) {
        assert(0 <= p and p < n);
        thrust(p += size);
        dat[p] = x;
        recalc(p);
    }

    X operator[](int p) {
        assert(0 <= p and p < n);
        thrust(p += size);
        return reflect(p);
    }

    X prod(int L, int R) {
        assert(0 <= L and L <= R and R <= n);
        if (L == R)
            return MX::unit();
        thrust(L += size);
        thrust((R += size - 1)++);
        X vl = MX::unit(), vr = MX::unit();
        while (L < R) {
            if (L & 1)
                MX::Rchop(vl, reflect(L++));
            if (R & 1)
                MX::Lchop(reflect(--R), vr);
            L >>= 1, R >>= 1;
        }
        return MX::op(vl, vr);
    }

    void apply(int l, int r, F f) {
        assert(0 <= l && l <= r && r <= n);
        if (l == r)
            return;
        thrust(l += size);
        thrust(r += size - 1);
        for (int L = l, R = r + 1; L < R; L >>= 1, R >>= 1) {
            if (L & 1)
                point_apply(L++, f);
            if (R & 1)
                point_apply(--R, f);
        }
        recalc(l);
        recalc(r);
    }
};

#line 2 "library/segtree/LazySegmentTree.hpp"

template <typename Lazy> class LazySegmentTree {
    using MX = typename Lazy::MX;
    using MF = typename Lazy::MF;
    using X = typename MX::value_type;
    using F = typename MF::value_type;
    int n, log, size;
    std::vector<X> dat;
    std::vector<F> laz;

    X reflect(int k) {
        if (k < size)
            return Lazy::mapping(laz[k], dat[k]);
        return dat[k];
    }
    void point_apply(int k, const F &f) {
        if (k < size)
            MF::Lchop(f, laz[k]);
        else
            dat[k] = Lazy::mapping(f, dat[k]);
    }
    void push(int k) {
        dat[k] = reflect(k);
        point_apply(2 * k, laz[k]);
        point_apply(2 * k + 1, laz[k]);
        laz[k] = MF::unit();
    }
    void thrust(int k) {
        for (int i = log; i; i--)
            push(k >> i);
    }
    void update(int i) { dat[i] = MX::op(reflect(2 * i), reflect(2 * i + 1)); }
    void recalc(int k) {
        while (k >>= 1)
            update(k);
    }

  public:
    LazySegmentTree() : LazySegmentTree(0) {}
    LazySegmentTree(int n) : LazySegmentTree(std::vector<X>(n, MX::unit())) {}
    LazySegmentTree(const std::vector<X> &v) : n(v.size()) {
        for (log = 1; (1 << log) < n; log++) {
        }
        size = 1 << log;
        dat.assign(size << 1, MX::unit());
        laz.assign(size, MF::unit());
        for (int i = 0; i < n; ++i)
            dat[size + i] = v[i];
        for (int i = size - 1; i >= 1; --i)
            update(i);
    }

    void set(int p, X x) {
        assert(0 <= p and p < n);
        thrust(p += size);
        dat[p] = x;
        recalc(p);
    }

    X operator[](int p) {
        assert(0 <= p and p < n);
        thrust(p += size);
        return reflect(p);
    }

    X prod(int L, int R) {
        assert(0 <= L and L <= R and R <= n);
        if (L == R)
            return MX::unit();
        thrust(L += size);
        thrust((R += size - 1)++);
        X vl = MX::unit(), vr = MX::unit();
        while (L < R) {
            if (L & 1)
                MX::Rchop(vl, reflect(L++));
            if (R & 1)
                MX::Lchop(reflect(--R), vr);
            L >>= 1, R >>= 1;
        }
        return MX::op(vl, vr);
    }

    void apply(int l, int r, F f) {
        assert(0 <= l && l <= r && r <= n);
        if (l == r)
            return;
        thrust(l += size);
        thrust(r += size - 1);
        for (int L = l, R = r + 1; L < R; L >>= 1, R >>= 1) {
            if (L & 1)
                point_apply(L++, f);
            if (R & 1)
                point_apply(--R, f);
        }
        recalc(l);
        recalc(r);
    }
};

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