luogu P3391 【模板】文艺平衡树（Splay） 非旋转treap

Code:

#include<bits/stdc++.h>
using namespace std;
void setIO(string s)
{
    string in=s+".in";
    string out=s+".out";
    freopen(in.c_str(),"r",stdin);
    freopen(out.c_str(),"w",stdout);
}
namespace fhqtreap
{
    #define maxn 300000
    #define lson ls[x]
    #define rson rs[x]
    int n,m,root;
    int rev[maxn],val[maxn],key[maxn],rs[maxn],ls[maxn],siz[maxn];
    void pushup(int x)
    {
        siz[x]=siz[lson]+siz[rson]+1;
    }
    void mark(int x)
    {
        if(!x)return;
        swap(lson, rson), rev[x] ^= 1;
    }
    void pushdown(int x)
    {
        if(!x || !rev[x]) return;
        mark(lson), mark(rson), rev[x] = 0;
    }
    void split(int x, int k, int &l, int &r)
    {
        if(x)
        {
            pushdown(x);
            if(k<=siz[lson])
            {
                r = x;
                split(lson, k, l, ls[r]);
                pushup(r);
            }
            else
            {
                l = x;
                split(rson, k - siz[lson] - 1, rs[l], r);
                pushup(l);
            }
        }
        else l = r = 0;
    }
    int merge(int x,int y)
    {
        if(!x || !y) return x + y;
        pushdown(x), pushdown(y);
        if(key[x] < key[y])
        {
            ls[y] = merge(x, ls[y]);
            pushup(y);
            return y;
        }
        else
        {
            rs[x] = merge(rs[x], y);
            pushup(x);
            return x;
        }
    }
    void print(int x)
    {
        if(!x) return;
        pushdown(x);
        print(lson), printf("%d ",val[x]), print(rson);
    }
    int main()
    {
        scanf("%d%d",&n,&m);
        for(int i=1;i<=n;++i)
        {
            key[i]=rand(), val[i]=i, siz[i]=1;
            root=merge(root, i);
        }
        for(int x,y,a=0,b=0,c=0,i=1;i<=m;++i)
        {
            scanf("%d%d",&x,&y);        // 反转 [x,y]
            a = b = c = 0;
            split(root, y, a, c);       // [1,y] -> a
            split(a, x - 1, a, b);      // [1,x-1] -> a
            mark(b);
            root = merge(merge(a,b),c);
        }
        print(root);
        return 0;
    }
};
int main()
{
    // setIO("input");
    fhqtreap :: main();
    return 0;
}