2018牛客多校第三场 C.Shuffle Cards

题意：

　　给出一段序列，每次将从第p个数开始的s个数移到最前面。求最终的序列是什么。

题解：

　　Splay翻转模板题。存下板子。

#include <bits/stdc++.h>
using namespace std;
const int INF = 1e6;
const int N = 1e5+;
int n, m;
int s, t;
int root, sz, tot;
int key[N], f[N], size[N], delta[N], cnt[N], ch[N][];
int a[N], ans[N];
int get(int x) {
    return ch[f[x]][] == x;
}
void update(int x) {
    if(x) {
        size[x] = cnt[x];
        if(ch[x][]) size[x] += size[ch[x][]];
        if(ch[x][]) size[x] += size[ch[x][]];
    }
}
int build(int l, int r, int fa) {
    if (l > r) return ;
    int mid = l+r>>;
    int now = ++sz;
    key[now] = a[mid]; f[now] = fa; cnt[now] = ;
    int lch = build(l, mid-, now);
    int rch = build(mid+, r, now);
    ch[now][] = lch, ch[now][] = rch;
    update(now);
    return now;
}
void pushdown(int x) {
    if(x && delta[x]) {
        swap(ch[x][], ch[x][]);
        delta[ch[x][]] ^= ; delta[ch[x][]] ^= ;
        delta[x] = ;
    }
}
void rotate(int x) {
    pushdown(f[x]);
    pushdown(x);
    int old = f[x], oldf = f[old], which = get(x);
    ch[old][which] = ch[x][which^]; f[ch[old][which]] = old;
    f[old] = x; ch[x][which^] = old;
    f[x] = oldf;
    if(oldf) ch[oldf][ch[oldf][]==old] = x;
    update(old); update(x);
}
void splay(int x, int tar) {
    for(int fa; (fa = f[x])!=tar; rotate(x))
        if(f[fa] != tar)
            rotate((get(x)==get(fa))?fa:x);
    if(!tar) root = x;
}
int find(int x) {
    int now = root, fa = ;
    while() {
        pushdown(now);
        if(x <= size[ch[now][]])
            now = ch[now][];
        else {
            x -= size[ch[now][]]+;
            if(x == ) return now;
            now = ch[now][];
        }
    }
}
void print(int now) {
    pushdown(now);
    if(ch[now][]) print(ch[now][]);
    if(key[now]!=-INF && key[now]!=INF) ans[++tot] = key[now];
    if(ch[now][]) print(ch[now][]);
}
int main() {
    scanf("%d%d", &n, &m);
    a[] = -INF; a[n+] = INF;
    for(int i = ; i <= n+; i++) a[i] = i-;
    root = build(, n+, );
    while(m--) {
        scanf("%d%d", &s, &t);
        if(s == ) continue;
        int f1 = find();
        int f2 = find(s+t+);
        splay(f1, );
        splay(f2, f1);
        delta[ch[ch[root][]][]] ^= ;
        f2 = find(t+);
        splay(f2, f1);
        delta[ch[ch[root][]][]] ^= ;
        f1 = find(t+);
        f2 = find(s+t+);
        splay(f1, );
        splay(f2, f1);
        delta[ch[ch[root][]][]]^=;
    }
    print(root);
    for(int i = ; i < n; i++) printf("%d ", ans[i]);
    printf("%d\n", ans[n]);
}