BZOJ 1500|NOI 2005|维修数列|Splay

这题没啥好说的。。主要是用来贴模板 3.6s
尝试了抽象Splay这个类，不过卡在了内存池怎么写的问题上。。。感觉对C++理解还不够深刻。

#include <cstdio>#include <stdexcept>#include <algorithm>using namespace std;#define inf 1000000000#define N 1000005int read() {    int s = 0, f = 1; char ch = getchar();    for (; ch < '0' || ch > '9'; ch = getchar()) if (ch == '-') f = -1;    for (; '0' <= ch && ch <= '9'; ch = getchar()) s = s * 10 + ch - '0';    return s * f;}template<typename T>class Splay {public:    Splay(T a[], int n) {        init(a, n);    }    void cover(int startIndex, int length, T val) {        Node *x = subsequence(startIndex, length), *y = x->fa;        cover_impl(x, val);        update(y); update(y->fa);    }    void reverse(int startIndex, int length) {        Node *x = subsequence(startIndex, length), *y = x->fa;        if (!x->tag) {            reverse_impl(x);            update(y); update(y->fa);        }    }    void erase(int startIndex, int length) {        Node *x = subsequence(startIndex, length), *y = x->fa;        delete_recursively(x); y->left() = Node::null;        update(y); update(y->fa);    }    T getSum(int startIndex, int length) {        return subsequence(startIndex, length)->sum;    }    T getMaxSubsequence() {        return root->mx;    }    void insert(T a[], int startIndex, int length) {        Node *z = build(a, 0, length - 1);        Node *x = find(root, startIndex + 1);        Node *y = find(root, startIndex + 2);        splay(x, root);        splay(y, x->right());        z->fa = y; y->left() = z;        update(y); update(x);    }private:    struct Node {        Node *c[2], *fa;        int size;        T sum, val, mx, lx, rx;        bool tag, rev;        Node(T v) {            c[0] = c[1] = fa = Node::null;            size = 1;            sum = val = mx = v;            if (v >= 0) lx = rx = v;            else lx = rx = 0;            tag = rev = 0;        }        Node *&left() { return c[0]; }        Node *&right() { return c[1]; }        void *operator new(size_t size) {            static Node *preserve = NULL;            static int cnt = 0;            Node *r;            if (free_pointer == null) {                // allocate memory lazily                if (preserve == NULL || cnt == 0) {                    preserve = (Node *) malloc(size * N);                    cnt = N;                }                r = &preserve[--cnt];            } else {                // reuse recycled memory                r = free_pointer;                free_pointer = free_pointer->fa;            }            return r;        }        void operator delete(void *p) {            if (p == NULL || p == null) return;            Node *q = static_cast<Node *>(p);            q->fa = free_pointer;            free_pointer = q;        }        static Node *null;    private:        Node() {            c[0] = c[1] = fa = this;            sum = size = val = lx = rx = tag = rev = 0;            mx = -inf;        }        static Node *free_pointer;    } *root;    void update(Node *x) {        if (x == Node::null) return;        Node *l = x->left(), *r = x->right();        x->sum = l->sum + r->sum + x->val;        x->size = l->size + r->size + 1;        x->mx = max(max(l->mx, r->mx), l->rx + x->val + r->lx);        x->lx = max(l->lx, l->sum + x->val + r->lx);        x->rx = max(r->rx, r->sum + x->val + l->rx);    }    void cover_impl(Node *c, T val) {        if (c == Node::null || c == NULL)            return;        c->tag = 1;        c->val = val;        c->sum = val * c->size;        if (val >= 0) {            c->lx = c->rx = c->mx = c->sum;        } else {            c->lx = c->rx = 0;            c->mx = val;        }    }    void reverse_impl(Node *x) {        if (x == Node::null || x == NULL)            return;        x->rev ^= 1;        swap(x->left(), x->right());        swap(x->lx, x->rx);    }    void pushdown(Node *x) {        Node *l = x->left(), *r = x->right();        if (x->tag) {            cover_impl(l, x->val);            cover_impl(r, x->val);            x->rev = x->tag = 0;        }        if (x->rev) {            x->rev ^= 1;            reverse_impl(x->left());            reverse_impl(x->right());        }    }    void rotate(Node *x, Node *&dest) {        Node *y = x->fa, *z = y->fa;        int l = y->right() == x, r = l ^ 1;        if (y == dest) dest = x;        else z->c[z->right() == y] = x;        x->c[r]->fa = y; y->fa = x; x->fa = z;        y->c[l] = x->c[r]; x->c[r] = y;        update(y); update(x);    }    void splay(Node *x, Node *&dest) {        while (x != dest) {            Node *y = x->fa, *z = y->fa;            if (y != dest) {                if ((y->left() == x) ^ (z->left() == y)) rotate(x, dest);                else rotate(y, dest);            }            rotate(x, dest);        }    }    Node *find(Node *x, int rank) {        pushdown(x);        if (x->left()->size + 1 == rank)            return x;        if (x->left()->size >= rank)            return find(x->left(), rank);        return find(x->right(), rank - x->left()->size - 1);    }    void delete_recursively(Node *x) {        if (x == Node::null) return;        delete_recursively(x->left());        delete_recursively(x->right());        delete x;    }    Node *&subsequence(int startIndex, int length) {        // for initialization, adding -oo forward and backward.        Node *x = find(root, startIndex), *y = find(root, startIndex + length + 1);        splay(x, root); splay(y, x->right());        return y->left();    }    void init(T a[], int n) {        for (int i = n; i; --i)            a[i] = a[i - 1];        a[0] = a[n + 1] = -inf;        root = build(a, 0, n + 1);    }    Node *build(T a[], int l, int r, Node *fa = Node::null) {        if (l > r) return Node::null;        int mid = (l + r) / 2;        Node *now = new Node(a[mid]);        now->fa = fa;        if (l != r) {            now->left() = build(a, l, mid - 1, now);            now->right() = build(a, mid + 1, r, now);        }        update(now);        return now;    }};template<typename T> typename Splay<T>::Node *Splay<T>::Node::null = new Node();template<typename T> typename Splay<T>::Node *Splay<T>::Node::free_pointer = Node::null;int main() {    static int a[N];    int i, n, m, k, tot, val;    char ch[10];    n = read(); m = read();    for (i = 0; i < n; ++i) a[i] = read();    Splay<int> *splay = new Splay<int>(a, n);    while(m--) {        scanf("%s", ch);        if (ch[0] != 'M' || ch[2] != 'X') k = read(), tot = read();        if (ch[0] == 'I') {            for (i = 0; i < tot; ++i) a[i] = read();            splay->insert(a, k, tot);        }        if (ch[0] == 'D') splay->erase(k, tot);        if (ch[0] == 'M') {            if (ch[2] == 'X') printf("%d\n", splay->getMaxSubsequence());            else val = read(), splay->cover(k, tot, val);        }        if (ch[0] == 'R') splay->reverse(k, tot);        if (ch[0] == 'G') printf("%d\n", splay->getSum(k, tot));    }    return 0;}