Splay 模板

Splay 模板

struct SplayTree{

    const static int maxn = 1e5 + 15;

	int ch[maxn][2] , key[maxn] , s[maxn] , tot , root , fa[maxn];

	void init( int x , int val = 0 , int par = 0 ){
		ch[x][0]=ch[x][1]=0 , fa[x]= par , key[x] = val , s[x] = 1;
	}

	void init(){
		init( 0 , 0 , 0 ); s[0] = 0;
		tot = root = 0 ;
	}

	inline void up(int x){
		s[x] = s[ch[x][0]] + s[ch[x][1]] + 1;
    } 

    void rotate( int x, int d ){
        int y = fa[x];
        ch[y][d ^ 1] = ch[x][d];
        if ( ch[x][d]) fa[ch[x][d]] = y;
        fa[x] = fa[y];
        if (fa[y]){
            if (y == ch[fa[y]][d])  ch[fa[y]][d] = x;
            else  ch[fa[y]][d ^ 1] = x;
        }
        ch[x][d] = y , fa[y] = x;
        up( y ) , up( x );
    }

    // Splay x to target's son
    void Splay( int x , int target ){
    	while( fa[x] != target ){
    		int y = fa[x];
    		if( x == ch[y][0] ){
    			if( fa[y] != target && y == ch[fa[y]][0])
    				rotate( y , 1 );
    			rotate( x , 1 );
    		}else{
    			if( fa[y] != target && y == ch[fa[y]][1])
    				rotate( y , 0 );
    			rotate( x , 0 );
    		}
    	}
    	if( !target ) root = x;
    }

 	void Insert( int & t , int val , int par = 0 ){
		if( t == 0 ){
			t = ++ tot;
			init( t , val , par );
			Splay( tot , 0 );
		}else{
			int cur = t;
			if( val < key[t] ) Insert( ch[t][0] , val , cur );
			else Insert( ch[t][1] , val , cur );
			up( cur );
		}
	}

	// Return point
	int find( int t , int v ){
		if( t == 0 ) return 0;
		else if( key[t] == v ){
			Splay( t , 0 );
			return t;
		}
		else if( v < key[t] ) return find( ch[t][0] , v );
		return find( ch[t][1] , v );
	}

	// Delete Root
	void Delete(){
		if( !ch[root][0] ){
			fa[ ch[root][1] ] = 0 ;
			root = ch[root][1];
		}else{
			int cur = ch[root][0];
			while( ch[cur][1] ) cur = ch[cur][1];
			Splay( cur , root );
			ch[cur][1] = ch[root][1];
			root = cur , fa[cur] = 0 , fa[ch[root][1]] = root;
			up( root );
		}
	}

	int size(){
    	return s[root];
    }
    // 查第 k 小 , 必须保证合法
    int kth( int x , int k ){
    	if( k == s[ch[x][0]] + 1 ){
    		Splay( x , 0 );
    		return key[x];
    	}
    	else if( k <= s[ch[x][0]] ) return kth( ch[x][0] , k );
    	else return kth( ch[x][1] , k - s[ch[x][0]] - 1 );
    } 

    //找前驱
    int pred( int t , int v ){
    	if( t == 0 ) return v;
    	else{
    		if( v <= key[t] ) return pred( ch[t][0] , v );
    		else{
    			int ans =  pred( ch[t][1] , v );
    			if( ans == v ){
    				ans = key[t];
    				Splay( t , 0 );
    			}
    			return ans;
    		}
    	}
    }

    /*int less( int t , int v ){
    	if( t == 0 ) return 0;
    	int rs = 0;
    	if( v <= key[t] ) rs = less( ch[t][0] , v );
    	else rs = s[ch[t][0]] + 1 + less( ch[t][1] , v );
    	if( Tl ){
    		Splay( t , 0 );
    		Tl = 0;
    	}
    	return rs;
    }*/

    //找后继
    int succ( int t , int v ){
    	if( t == 0 ) return v;
    	else{
    		if( v >= key[t] ) return succ( ch[t][1] , v );
    		else{
    			int ans =  succ( ch[t][0] , v );
    			if( ans == v ){
    				ans = key[t];
    				Splay( t , 0 );
    			}
    			return ans;
    		}
    	}
    }

	void Preorder( int t ){
		if( !t ) return;
		Preorder( ch[t][0] );
		printf("%d " , key[t] );
		Preorder( ch[t][1] );
	}

}splay;