【HDU】4453 Looploop 【splay】

传送门：【HDU】4453 Looploop

题目分析：本题就是splay的基本应用，一个环其实可以看成一条链，如果是move操作，要么将尾巴剪切到头部，要么将头部剪切到尾巴，就这样。其他的操作都是很普通的了。

1Y啊还真爽啊，不过因为逗比的将rotate写错了。。有点无语。。。

还有就是本题的操作有很大的特殊性，按着这个特殊性写效率可以提高很多的吧应该。。我没利用特殊性

代码如下：

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std ;

#define REP( i , a , b ) for ( int i = ( a ) ; i < ( b ) ; ++ i )
#define FOR( i , a , b ) for ( int i = ( a ) ; i <= ( b ) ; ++ i )
#define REV( i , a , b ) for ( int i = ( a ) ; i >= ( b ) ; -- i )
#define CLR( a , x ) memset ( a , x , sizeof a )

const int MAXN = 200000 ;

struct SplayNode {
	SplayNode* c[2] ;
	SplayNode* f ;
	int v ;
	int s ;
	bool rev ;
	int addv ;
	
	SplayNode () : s ( 0 ) {}
	
	void add ( int x ) {
		v += x ;
		addv += x ;
	}
	
	void pushup () {
		s = c[0] -> s + c[1] -> s + 1 ;
	}
	
	void pushdown () {
		if ( rev ) {
			swap ( c[0] , c[1] ) ;
			c[0] -> rev ^= 1 ;
			c[1] -> rev ^= 1 ;
			rev = 0 ;
		}
		if ( addv ) {
			c[0] -> add ( addv ) ;
			c[1] -> add ( addv ) ;
			addv = 0 ;
		}
	}
} Tnull , *null = &Tnull ;

struct Splay {
	SplayNode node[MAXN] ;
	SplayNode* cur ;
	SplayNode* root ;
	
	Splay () : root ( null ) , cur ( node ) {}
	
	void clear () {
		root = null ;
		cur = node ;
	}
	
	SplayNode* newNode ( int v , SplayNode* f ) {
		cur -> v = v ;
		cur -> s = 1 ;
		cur -> rev = 0 ;
		cur -> addv = 0 ;
		cur -> f = f ;
		cur -> c[0] = cur -> c[1] = null ;
		return cur ++ ;
	}
	
	void init ( int n , int element[] ) {
		clear () ;
		FOR ( i , 0 , n + 1 ) {
			SplayNode* o = newNode ( element[i] , null ) ;
			o -> c[0] = root ;
			root -> f = o ;
			root = o ;
			root -> pushup () ;
		}
	}
	
	void rotate ( SplayNode* o , bool d ) {
		SplayNode* p = o -> f ;
		p -> pushdown () ;
		o -> pushdown () ;
		p -> c[!d] = o -> c[d] ;
		o -> c[d] -> f = p ;
		o -> f = p -> f ;
		if ( p -> f != null ) {
			if ( p == p -> f -> c[0] ) p -> f -> c[0] = o ;
			else p -> f -> c[1] = o ;
		}
		o -> c[d] = p ;
		p -> f = o ;
		p -> pushup () ;
		if ( root == p ) root = o ;
	}
	
	void splay ( SplayNode* o , SplayNode* f ) {
		while ( o -> f != f ) {
			SplayNode* p = o -> f ;
			if ( p -> f == f ) {
				if ( o == p -> c[0] ) rotate ( o , 1 ) ;
				else                  rotate ( o , 0 ) ;
			} else {
				if ( p == p -> f -> c[0] ) {
					if ( o == p -> c[0] ) rotate ( p , 1 ) , rotate ( o , 1 ) ;
					else                  rotate ( o , 0 ) , rotate ( o , 1 ) ;
				} else {
					if ( o == p -> c[1] ) rotate ( p , 0 ) , rotate ( o , 0 ) ;
					else                  rotate ( o , 1 ) , rotate ( o , 0 ) ;
				}
			}
		}
		o -> pushup () ;
	}
	
	void select ( int k , SplayNode* f ) {
		SplayNode* o = root ;
		++ k ;
		while ( o != null ) {
			o -> pushdown () ;
			int s = o -> c[0] -> s ;
			if ( k == s + 1 ) break ;
			if ( k <= s ) o = o -> c[0] ;
			else {
				k -= s + 1 ;
				o = o -> c[1] ;
			}
		}
		splay ( o , f ) ;
	}
	
	SplayNode* get ( int l , int r ) {
		select ( l - 1 , null ) ;
		select ( r + 1 , root ) ;
		return root -> c[1] -> c[0] ;
	}
	
	void split ( int l , int r , SplayNode* &o ) {
		o = get ( l , r ) ;
		o -> f = null ;
		root -> c[1] -> c[0] = null ;
		root -> c[1] -> pushup () ;
		root -> pushup () ;
	}
	
	void merge ( int pos , SplayNode* o ) {
		get ( pos + 1 , pos ) ;
		o -> f = root -> c[1] ;
		root -> c[1] -> c[0] = o ;
		root -> c[1] -> pushup () ;
		root -> pushup () ;
		splay ( o , null ) ;
	}
	
	void cut ( int l , int r , int pos ) {
		SplayNode* o ;
		split ( l , r , o ) ;
		merge ( pos , o ) ;
	}
	
	void reverse ( int l , int r ) {
		SplayNode* o = get ( l , r ) ;
		o -> rev ^= 1 ;
		splay ( o , null ) ;
	}
	
	void add ( int l , int r , int v ) {
		SplayNode* o = get ( l , r ) ;
		o -> add ( v ) ;
		splay ( o , null ) ;
	}
	
	void insert ( int pos , int v ) {
		get ( pos + 1 , pos ) ;
		SplayNode* o = newNode ( v , root -> c[1] ) ;
		root -> c[1] -> c[0] = o ;
		root -> c[1] -> pushup () ;
		root -> pushup () ;
		splay ( o , null ) ;
	}
	
	void remove ( int pos ) {
		SplayNode* o ;
		split ( pos , pos , o ) ;
		root -> c[1] -> c[0] = null ;
		root -> c[1] -> pushup () ;
		root -> pushup () ;
	}
	
	int query ( int pos ) {
		select ( pos , null ) ;
		return root -> v ;
	}
	
	void print ( SplayNode* o ) {
		if ( o -> c[0] != null ) print ( o -> c[0] ) ;
		printf ( "left->v = %d , o->v = %d , right->v = %d\n" , o -> c[0] -> v , o -> v , o -> c[1] -> v ) ;
		if ( o -> c[1] != null ) print ( o -> c[1] ) ;
	}
	
} SplayTree ;

int element[MAXN] ;
int n , m , k1 , k2 ;
int x ;
char s[10] ;

void solve () {
	element[0] = element[n + 1] = 0 ;
	FOR ( i , 1 , n ) scanf ( "%d" , element + i ) ;
	SplayTree.init ( n , element ) ;
	//SplayTree.print ( SplayTree.root ) ;
	while ( m -- ) {
		scanf ( "%s" , s ) ;
		if ( s[0] == 'q' ) {
			printf ( "%d\n" , SplayTree.query ( 1 ) ) ;
		} else if ( s[0] == 'i' ) {
			scanf ( "%d" , &x ) ;
			SplayTree.insert ( 1 , x ) ;
			++ n ;
		} else if ( s[0] == 'a' ) {
			scanf ( "%d" , &x ) ;
			SplayTree.add ( 1 , k2 , x ) ;
		} else if ( s[0] == 'r' ) {
			SplayTree.reverse ( 1 , k1 ) ;
		} else if ( s[0] == 'd' ) {
			SplayTree.remove ( 1 ) ;
			-- n ;
		} else {
			scanf ( "%d" , &x ) ;
			if ( x == 1 ) SplayTree.cut ( n , n , 0 ) ;
			else SplayTree.cut ( 1 , 1 , n - 1 ) ;
		}
	}
}

int main () {
	int cas = 0 ;
	while ( ~scanf ( "%d%d%d%d" , &n , &m , &k1 , &k2 ) && ( n || m || k1 || k2 ) ) {
		printf ( "Case #%d:\n" , ++ cas ) ;
		solve () ;
	}
	return 0 ;
}