题解 P5055 【【模板】可持久化文艺平衡树】

Aleph1022 · 2018-12-01 18:00:25 · 题解

啥时候“文艺平衡树”成了 Splay 的代称了……

果断写了个 FHQ Treap，然后 30pts。
求助大佬之后发现标记下传时也要新建结点。

以及合并的时候不必新建结点，因为分裂时已经新建了，否则会 MLE。

代码：

#include <cstdio>
#include <algorithm>
#include <cstdlib>
#define ls(p) tree[p].lson
#define rs(p) tree[p].rson
using namespace std;
const int N = 2e5;
int n;
long long lastans;
struct node
{
    int rnd,sz,rev;
    long long val,sum;
    int lson,rson;
} tree[(N << 7) + 10];
int rt[N + 10];
inline int new_node(long long v = 0)
{
    static int tot = 0;
    tree[++tot].val = v;
    tree[tot].sum = v;
    tree[tot].rnd = rand();
    tree[tot].sz = 1;
    return tot;
}
inline int copy_node(int p)
{
    int ret = new_node();
    tree[ret] = tree[p];
    return ret;
}
inline void up(int p)
{
    tree[p].sz = tree[ls(p)].sz + 1 + tree[rs(p)].sz;
    tree[p].sum = tree[ls(p)].sum + tree[p].val + tree[rs(p)].sum;
}
inline void down(int p)
{
    if(tree[p].rev)
    {
        if(ls(p))
            ls(p) = copy_node(ls(p));
        if(rs(p))
            rs(p) = copy_node(rs(p));
        swap(ls(p),rs(p));
        if(ls(p))
            tree[ls(p)].rev ^= 1;
        if(rs(p))
            tree[rs(p)].rev ^= 1;
        tree[p].rev = 0;
    }
}
void split(int p,int k,int &x,int &y)
{
    if(!p)
    {
        x = y = 0;
        return ;
    }
    down(p);
    if(tree[ls(p)].sz < k)
        x = copy_node(p),split(rs(x),k - tree[ls(p)].sz - 1,rs(x),y),up(x);
    else
        y = copy_node(p),split(ls(y),k,x,ls(y)),up(y);
}
int merge(int x,int y)
{
    if(!x || !y)
        return x | y;
    down(x),down(y);
    if(tree[x].rnd < tree[y].rnd)
    {
        rs(x) = merge(rs(x),y);
        up(x);
        return x;
    }
    else
    {
        ls(y) = merge(x,ls(y));
        up(y);
        return y;
    }
}
int main()
{
    srand(19260817);
    scanf("%d",&n);
    int cnt = 0;
    int v,op;
    long long a,b;
    int x,y,z;
    while(n--)
    {
        scanf("%d%d",&v,&op);
        if(op == 1)
        {
            scanf("%lld%lld",&a,&b);
            a ^= lastans,b ^= lastans;
            split(rt[v],a,x,y);
            rt[++cnt] = merge(merge(x,new_node(b)),y);
        }
        else if(op == 2)
        {
            scanf("%lld",&a);
            a ^= lastans;
            split(rt[v],a,x,z);
            split(x,a - 1,x,y);
            rt[++cnt] = merge(x,z);
        }
        else if(op == 3)
        {
            scanf("%lld%lld",&a,&b);
            a ^= lastans,b ^= lastans;
            split(rt[v],b,x,z);
            split(x,a - 1,x,y);
            tree[y].rev ^= 1;
            rt[++cnt] = merge(merge(x,y),z);
        }
        else
        {
            scanf("%lld%lld",&a,&b);
            a ^= lastans,b ^= lastans;
            split(rt[v],b,x,z);
            split(x,a - 1,x,y);
            printf("%lld\n",lastans = tree[y].sum);
            rt[++cnt] = merge(merge(x,y),z);
        }
    }
}