Shuffle Cards（牛客第三场+splay）

题目：

题意：将1~n的数进行m次操作，每次操作将第pi位到pi+si-1位的数字移到第一位，求最后的排列。

思路：现在还没不会写splay，在知道这是splay模板题后找了一波别人的模板，虽然过了，但是感觉自己没学到什么，过几天去学一波splay，再回来把这题重写一次~

代码实现如下：

#include <map>
#include <set>
#include <cmath>
#include <ctime>
#include <stack>
#include <queue>
#include <cstdio>
#include <cctype>
#include <bitset>
#include <string>
#include <vector>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <functional>
#include <bits/stdc++.h>
#define debug(x) cout<<"["<<x<<"]";
#define FIN freopen("input.txt","r",stdin);
#define FOUT freopen("output.txt","w+",stdout);

inline int read() {//读入挂
    int ret = 0, c, f = 1;
    for(c = getchar(); !(isdigit(c) || c == '-'); c = getchar());
    if(c == '-')
        f = -1, c = getchar();
    for(; isdigit(c); c = getchar())
        ret = ret * 10 + c - '0';
    if(f < 0)
        ret = -ret;
    return ret;
}

const int MX = 1e5 + 7;
const int INF = 0x3f3f3f3f;

int size[MX];
int num[MX], col[MX], n, m;
int son[MX][2], fa[MX], root, sz;
void Link(int x, int y, int c) {
    fa[x] = y;
    son[y][c] = x;
}
void push_up(int rt) {
    size[rt] = size[son[rt][0]] + size[son[rt][1]] + 1;
}
void push_down(int rt) {
    if(col[rt]) {
        col[son[rt][0]] ^= 1;
        col[son[rt][1]] ^= 1;
        int x = son[rt][0];
        son[rt][0] = son[rt][1];
        son[rt][1] = x;
        col[rt] = 0;
    }
}
void Rotate(int x, int c) {
    int y = fa[x];
    push_down(y);
    push_down(x);
    Link(x, fa[y], son[fa[y]][1] == y);
    Link(son[x][!c], y, c);
    Link(y, x, !c);
    push_up(y);
} /*把节点x旋转到g的下面*/

void Splay(int x, int g) {
    push_down(x);    /*剪断[a,b]放到c后面*/
    while(fa[x] != g) {
        int y = fa[x], cx = son[y][1] == x, cy = son[fa[y]][1] == y;
        if(fa[y] == g)
            Rotate(x, cx);
        else {
            if(cx == cy)
                Rotate(y, cy);
            else
                Rotate(x, cx);
            Rotate(x, cy);
        }
    }
    push_up(x);
    if(!g)
        root = x;
}
void NewNode(int f, int &rt) {
    rt = ++sz;
    fa[rt] = f, size[rt] = 1;
    son[rt][0] = son[rt][1] = col[rt] = 0;
} /*把第k个找出来，放到g的下面*/ int Select(int k, int g) {
    int rt = root;
    while(size[son[rt][0]] != k) {
        if(size[son[rt][0]] > k)
            rt = son[rt][0];
        else
            k -= size[son[rt][0]] + 1, rt = son[rt][1];
        push_down(rt);
    }
    Splay(rt, g);
    return rt;
}
void Build(int l, int r, int &rt, int f) {
    if(l > r)
        return;
    int m = (l + r) >> 1, t;
    NewNode(f, rt);
    num[rt] = m;
    Build(l, m - 1, son[rt][0], rt);
    Build(m + 1, r, son[rt][1], rt);
    push_up(rt);
}
void Prepare(int n) {
    sz = 0;
    NewNode(0, root);
    num[1] = 0;
    NewNode(root, son[root][1]);
    num[2] = 0;
    Build(1, n, son[2][0], 2);
    Splay(3, 0);
}
void Print(int rt, int &DFN) {
    if(!rt)
        return;
    push_down(rt);
    Print(son[rt][0], DFN);
    if(num[rt])
        printf("%d%c", num[rt], ++DFN == n ? '
' : ' ');
    Print(son[rt][1], DFN);
}
void Flip(int l, int r) {
    Select(l - 1, 0);
    Select(r + 1, root);
    col[son[son[root][1]][0]] ^= 1;
}

void Cut(int a, int b, int c) {
    Select(a - 1, 0);    /*平衡树操作*/
    Select(b + 1, root);
    int w = son[son[root][1]][0];
    son[son[root][1]][0] = 0;
    Splay(son[root][1], 0);
    Select(c, 0);
    Select(c + 1, root);
    son[son[root][1]][0] = w;
    Splay(son[root][1], 0);
}
void NewNode(int f, int x, int &rt) {
    rt = ++sz;
    fa[rt] = f, size[rt] = 1;
    son[rt][0] = son[rt][1] = 0;
    num[rt] = x;
}
int Kth(int k) {
    int rt = root;
    while(size[son[rt][0]] != k) {
        if(size[son[rt][0]] > k)
            rt = son[rt][0];
        else
            k -= size[son[rt][0]] + 1, rt = son[rt][1];
    }
    Splay(rt, 0);
    return num[rt];
}
void Insert(int x) {
    int rt = root;
    while(true) {
        int nxt = x > num[rt];
        if(!son[rt][nxt]) {
            NewNode(rt, x, son[rt][nxt]);
            Splay(sz, 0);
            return;
        }
        rt = son[rt][nxt];
    }
}


int main() {
    while(~scanf("%d%d", &n, &m)) {
        Prepare(n);
        int x, y;
        for(int i = 0; i < m; i++) {
            scanf("%d%d", &x, &y);
            Cut(x, x + y - 1, 0);
        }
        int DFN = 0;
        Print(root, DFN);
    }
    return 0;
}