splay的题；
学习白书上和网上的代码敲的；
1 #include <cstdio> 2 #include <cstring> 3 #include <cstdlib> 4 #include <algorithm> 5 using namespace std; 6 int n,m; 7 struct node 8 { 9 node *ch[2]; 10 int s,v; 11 int flip; 12 node(int v):v(v) 13 { 14 ch[1]=ch[0]=NULL; 15 s=1; 16 flip=0; 17 } 18 void maintain() 19 { 20 s=1; 21 if(ch[0]!=NULL)s+=ch[0]->s; 22 if(ch[1]!=NULL)s+=ch[1]->s; 23 } 24 void pushdown() 25 { 26 if(flip) 27 { 28 flip=0; 29 swap(ch[0],ch[1]); 30 if(ch[0]!=NULL)ch[0]->flip=!ch[0]->flip; 31 if(ch[1]!=NULL)ch[1]->flip=!ch[1]->flip; 32 } 33 } 34 int cmp(int x)const 35 { 36 int t=(ch[0]==NULL)?0:ch[0]->s; 37 if(t>=x)return 0; 38 if(t+1==x)return -1; 39 return 1; 40 } 41 }; 42 void rotate(node* &root,int d) 43 { 44 node *k=root->ch[d^1]; 45 root->ch[d^1]=k->ch[d]; 46 k->ch[d]=root; 47 root=k; 48 root->ch[d]->maintain(); 49 root->maintain(); 50 } 51 52 void build(node* &root,int l,int r) 53 { 54 int mid=(l+r)>>1; 55 root=new node(mid); 56 if(l<mid)build(root->ch[0],l,mid-1); 57 if(r>mid)build(root->ch[1],mid+1,r); 58 root->maintain(); 59 } 60 61 void splay(node* &root,int k) 62 { 63 root->pushdown(); 64 int d=root->cmp(k); 65 if(d==1) 66 { 67 if(root->ch[0]!=NULL) 68 k-=root->ch[0]->s; 69 k--; 70 } 71 if(d!=-1) 72 { 73 node *p=root->ch[d]; 74 p->pushdown(); 75 int d2=p->cmp(k); 76 int k2=k; 77 if(d2==1) 78 { 79 if(p->ch[0]!=NULL) 80 k2-=p->ch[0]->s; 81 k2--; 82 } 83 if(d2!=-1) 84 { 85 splay(p->ch[d2],k2); 86 if(d==d2) rotate(root,d^1); 87 else rotate(root->ch[d],d); 88 } 89 rotate(root,d^1); 90 } 91 return; 92 } 93 94 void split(node *root,int k,node* &left,node* &right) 95 { 96 splay(root,k); 97 left=root; 98 right=root->ch[1]; 99 root->ch[1]=NULL; 100 left->maintain();//左边的要维护，右边不需要； 101 } 102 103 node *merge(node *left,node *right) 104 { 105 splay(left,left->s);// 106 left->ch[1]=right; 107 left->maintain(); 108 return left; 109 } 110 111 void dfs(node *root) 112 { 113 root->pushdown(); 114 if(root->ch[0])dfs(root->ch[0]); 115 if(root->v&&root->v!=n+1)printf("%d ",root->v); 116 if(root->ch[1])dfs(root->ch[1]); 117 } 118 119 void del(node *root) 120 { 121 if(root->ch[0])del(root->ch[0]); 122 if(root->ch[1])del(root->ch[1]); 123 delete root; 124 } 125 126 127 node *root; 128 int main() 129 { 130 int a,b; 131 while(scanf("%d%d",&n,&m)!=EOF) 132 { 133 root=NULL; 134 build(root,0,n+1); 135 while(m--) 136 { 137 scanf("%d%d",&a,&b); 138 node *right,*mid,*left,*tmp,*o; 139 split(root,a,left,o); 140 split(o,b-a+1,mid,right); 141 if(right->s>1) 142 { 143 split(right,right->s-1,tmp,o); 144 mid->flip^=1; 145 root=merge(left,merge(merge(tmp,mid),o)); 146 } 147 else 148 { 149 mid->flip^=1; 150 root=merge(left,merge(mid,right)); 151 } 152 } 153 dfs(root); 154 del(root); 155 } 156 return 0; 157 }