注意！本帖不是算法介绍！只是贴代码（逃）
//嫌stdlib的rand太慢，手打了一个
1 /* 2 Author: hotwords 3 */ 4 5 typedef unsigned int tkey; 6 class Random { 7 private: 8 tkey rs1,rs2,rs3; 9 public: 10 tkey operator()() { 11 rs1=(rs1<<9)^(rs2>>6)^rs3; 12 rs2=(rs2<<8)^(rs3>>7)^rs1; 13 rs3=(rs1<<7)^(rs2>>8)^rs2; 14 return rs1^rs2^rs3; 15 } 16 void seed(tkey x) { 17 rs1=x; 18 rs2=rs1^0x64db3c5e; 19 rs3=rs1^0xdb7a6f81; 20 } 21 Random() { 22 seed(0x86e241ca); 23 } 24 } random; 25 template<typename tp> 26 class Treap { 27 private: 28 class TNode { 29 private: 30 int p_size,p_csize; 31 public: 32 tp val;int cnt; 33 tkey key; 34 TNode *lc,*rc; 35 TNode(tp v) { 36 val=v;p_size=1; 37 p_csize=cnt=1; 38 key=random(); 39 lc=rc=0; 40 } 41 inline int size()const{return this?this->p_size:0;} 42 inline int csize()const{return this?this->p_csize:0;} 43 void combine() { 44 p_size=1+lc->size()+rc->size(); 45 p_csize=cnt+lc->csize()+rc->csize(); 46 } 47 void split(int k,TNode*& l,TNode*& r) { 48 if(!this) { 49 l=r=0;return; 50 } 51 if(k<=lc->size()) { 52 lc->split(k,l,r); 53 lc=r;r=this; 54 } else { 55 rc->split(k-lc->size()-1,l,r); 56 rc=l;l=this; 57 } 58 combine(); 59 } 60 tp min() const { 61 const TNode *cur=this; 62 while(cur->lc) cur=cur->lc; 63 return cur->val; 64 } 65 tp max() const { 66 const TNode *cur=this; 67 while(cur->rc) cur=cur->rc; 68 return cur->val; 69 } 70 } *root; 71 TNode* merge(TNode* l,TNode* r) { 72 if(!r) return l; 73 if(!l) return r; 74 if(l->key<r->key) { 75 l->rc=merge(l->rc,r); 76 l->combine(); 77 return l; 78 } else { 79 r->lc=merge(l,r->lc); 80 r->combine(); 81 return r; 82 } 83 } 84 public: 85 Treap(){root=0;} 86 int size()const{return root->size();} 87 int count()const{return root->csize();} 88 int rank(tp v) const { 89 int ans=0; 90 TNode *cur=root; 91 while(cur) { 92 if(v<cur->val) cur=cur->lc; 93 else { 94 ans+=cur->lc->csize(); 95 if(v>cur->val) ans+=cur->cnt,cur=cur->rc; 96 else return ans+1; 97 } 98 } 99 return ans; 100 } 101 int nrank(tp v) const { 102 int ans=0; 103 TNode *cur=root; 104 while(cur) { 105 if(v<cur->val) cur=cur->lc; 106 else ans+=cur->lc->size()+1,cur=cur->rc; 107 } 108 return ans; 109 } 110 void insert(tp v) { 111 int k=nrank(v); 112 TNode *l,*m,*r,*t; 113 root->split(k,t,r); 114 t->split(k-1,l,m); 115 if(m&&m->val==v) ++m->cnt,m->combine(); 116 else m=merge(m,new TNode(v)); 117 root=merge(merge(l,m),r); 118 } 119 void erase(tp v) { 120 int k=nrank(v); 121 TNode *l,*m,*r,*t; 122 root->split(k,t,r); 123 t->split(k-1,l,m); 124 if(!--m->cnt) { 125 delete []m;m=0; 126 } else m->combine(); 127 root=merge(merge(l,m),r); 128 } 129 tp get_kth(int k) const { 130 TNode *cur=root; 131 while(cur) { 132 if(k<=cur->lc->csize()) cur=cur->lc; 133 else { 134 k-=cur->lc->csize(); 135 if(k<=cur->cnt) return cur->val; 136 k-=cur->cnt;cur=cur->rc; 137 } 138 } 139 } 140 tp prev(tp v) { 141 int k=nrank(v); 142 TNode *l,*m,*r,*t; 143 tp ans; 144 root->split(k,t,r); 145 t->split(k-1,l,m); 146 ans=m->val<v?m->val:l->max(); 147 root=merge(merge(l,m),r); 148 return ans; 149 } 150 tp next(tp v) { 151 int k=nrank(v); 152 TNode *l,*r; 153 tp ans; 154 root->split(k,l,r); 155 ans=r->min(); 156 root=merge(l,r); 157 return ans; 158 } 159 };