hdu 4453 Looploop (伸展树)

hdu 4453 Looploop (伸展树)

题意：给出一个数列，然后又五个操作，维护这个数列.。

解题思路：splay tree 。其实这题就是考你伸展树的基本功了。唯一有点思维的地方，就是move的时候，对于两种move，第一种，把指针逆时针移一位，其实就是把最后一个元素插到最前面，在把最后那个删掉。。。第二种反之。

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std ;

const int maxn = 555555 ;
int col[maxn] , num[maxn] , val[maxn] , add[maxn] ;
int size[maxn] , son[2][maxn] , fa[maxn] , tot ;
int k1 , k2 ;

void rev ( int rt ) {
    if ( !rt ) return ;
    int ls = son[0][rt] , rs = son[1][rt] ;
    son[1][rt] = ls ;
    son[0][rt] = rs ;
    col[rt] ^= 1 ;
}

void push_up ( int rt ) {
    size[rt] = 1 ;
    if ( son[0][rt] ) size[rt] += size[son[0][rt]] ;
    if ( son[1][rt] ) size[rt] += size[son[1][rt]] ;
}

void push_down ( int rt ) {
    int ls = son[0][rt] , rs = son[1][rt] ;
    if ( add[rt] ) {
        if ( ls ) add[ls] += add[rt] , val[ls] += add[rt] ;
        if ( rs ) add[rs] += add[rt] , val[rs] += add[rt] ;
        add[rt] = 0 ;
    }
    if ( col[rt] ) {
        rev ( ls ) ;
        rev ( rs ) ;
        col[rt] = 0 ;
    }
}

int new_node ( ) {
    size[++tot] = 1 ;
    son[0][tot] = son[1][tot] = 0 , fa[tot] = 0 ;
    col[tot] = add[tot] = 0 ;
    return tot ;
}

int build ( int l , int r ) {
    if ( l > r ) return 0 ;
    int mid = l + r >> 1 ;
    int temp = new_node () ;
    val[temp] = num[mid] ;
    son[0][temp] = build ( l , mid - 1 ) ;
    son[1][temp] = build ( mid + 1 , r ) ;
    if ( son[0][temp] )
        fa[son[0][temp]] = temp , size[temp] += size[son[0][temp]] ;
    if ( son[1][temp] )
        fa[son[1][temp]] = temp , size[temp] += size[son[1][temp]] ;
        return temp ;
}

void rot ( int rt , int c ) {
    int y = fa[rt] , z = fa[y] ;
    push_down ( y ) , push_down ( rt ) ;
    son[!c][y] = son[c][rt] ;
    if ( son[c][rt] ) fa[son[c][rt]] = y ;
    fa[rt] = z ;
    if ( z ) {
        if ( y == son[0][z] ) son[0][z] = rt ;
        else son[1][z] = rt ;
    }
    son[c][rt] = y , fa[y] = rt ;
    push_up ( y ) ;
}

void splay ( int x , int to ) {
    push_down ( x ) ;
    while ( fa[x] != to ) {
        if ( fa[fa[x]] == to ) rot ( x , x == son[0][fa[x]] ) ;
        else {
            int y = fa[x] , z = fa[y] ;
            if ( x == son[0][y] ) {
                if ( y == son[0][z] ) rot ( y , 1 ) , rot ( x , 1 ) ;
                else rot ( x , 1 ) , rot ( x , 0 ) ;
            }
            else {
                if ( y == son[1][z] ) rot ( y , 0 ) , rot ( x , 0 ) ;
                else rot ( x , 0 ) , rot ( x , 1 ) ;
            }
        }
    }
    push_up ( x ) ;
}

int find ( int rt , int key ) {
    push_down ( rt) ;
    int cnt = 0 ;
    if ( son[0][rt] ) cnt = size[son[0][rt]] ;
    if ( cnt + 1 == key ) return rt ;
    if ( cnt + 1 > key ) return find ( son[0][rt] , key ) ;
    return find ( son[1][rt] , key - cnt - 1 ) ;
}

int insert ( int l , int x , int rt ) {
    int temp = find ( rt , l ) ;
    splay ( temp , 0 ) ;
    rt = temp ;
    temp = find ( rt , l + 1 ) ;
    splay ( temp , rt ) ;
    int t = new_node () ;
    val[t] = x ;
    son[0][temp] = t , fa[t] = temp ;
    push_up ( temp ) ;
    push_up ( rt ) ;
    return rt ;
}

int del ( int l , int r , int rt ) {
    int temp = find ( rt , l - 1 ) ;
    splay ( temp , 0 ) ;
    rt = temp ;
    temp = find ( rt , r + 1 ) ;
    splay ( temp , rt ) ;
    son[0][temp] = 0 ;
    push_up ( temp ) ;
    push_up ( rt ) ;
    return rt ;
}

void print ( int rt ) {
    push_down ( rt ) ;
    if ( son[0][rt] ) print ( son[0][rt] ) ;
    printf ( "%d " , val[rt] ) ;
    if ( son[1][rt] ) print ( son[1][rt] ) ;
}

int main () {
    int n , m , i , j , k , x , ca = 0 ;
    char s[111] ;
    while ( scanf ( "%d%d%d%d" , &n , &m , &k1 , &k2 ) != EOF ) {
        if ( n == 0 ) break ;
        for ( i = 1 ; i <= n ; i ++ )
            scanf ( "%d" , &num[i] ) ;
        printf ( "Case #%d:\n" , ++ ca ) ;
        tot = 0 ;
        int rt = build ( 0 , n + 1 ) ;
        while ( m -- ) {
            scanf ( "%s" , s ) ;
            if ( s[0] == 'q' ) {
                int temp = find ( rt , 2 ) ;
                splay ( temp , 0 ) ;
                rt = temp ;
                printf ( "%d\n" , val[rt] ) ;
            }
            else if ( s[0] == 'r' ) {
                int temp = find ( rt , 1 ) ;
                splay ( temp , 0 ) ;
                rt = temp ;
                temp = find ( rt , 2 + k1 ) ;
                splay ( temp , rt ) ;
                rev ( son[0][temp] ) ;
            }
            else if ( s[0] == 'i' ) {
                scanf ( "%d" , &x ) ;
                rt = insert ( 2 , x , rt ) ;
            }
            else if ( s[0] == 'd' ) {
                rt = del ( 2 , 2 , rt ) ;
            }
            else if ( s[0] == 'a' ) {
                scanf ( "%d" , &x ) ;
                int temp = find ( rt , 1 ) ;
                splay ( temp , 0 ) ;
                rt = temp ;
                temp = find ( rt , k2 + 2 ) ;
                splay ( temp , rt ) ;
                int fuck = son[0][temp] ;
                val[fuck] += x ;
                add[fuck] += x ;
                push_up ( temp ) ;
                push_up ( rt ) ;
            }
            else {
                scanf ( "%d" , &x ) ;
                if ( x == 2 ) {
                    int temp = find ( rt , 2 ) ;
                    temp = val[temp] ;
                    rt = del ( 2 , 2 , rt ) ;
                    int len = size[rt] ;
                    rt = insert ( len - 1 , temp , rt ) ;
                }
                else {
                    int len = size[rt] ;
                    int temp = find ( rt , len - 1 ) ;
                    temp = val[temp] ;
                    rt = del ( len - 1 , len - 1 , rt ) ;
                    rt = insert ( 1 , temp , rt ) ;
                }
            }
        }
    }
    return 0 ;
}