bzoj1014 火星人prefix Splay 字符串Hash

Posted 2020-10-08 Loser Of Life

链接：http://www.lydsy.com/JudgeOnline/problem.php?id=1014

题意：动态修改字符串，动态查询某两个后缀之间的$LCP$长度。

这题肯定一堆人刚开始：$woc$这题好水啊，后缀数据结构放肆撸啊……

等看到后半段：$woc$这个修改怎么改啊……

实际上这个东西跟后缀数据结构半毛钱关系没有……正确做法就是$Hash$……不停地插入字符，修改整棵子树的$Hash$值，然后就是动态的修改$Hash$值……转啊转……修改……转……然后就出来了……

  1 #include<iostream>
  2 #include<cstdio>
  3 #include<algorithm>
  4 #include<cstring>
  5 #define ls(x) ((x)->ch[0])
  6 #define rs(x) ((x)->ch[1])
  7 #define fa(x) (x->pa)
  8 using namespace std;
  9 const int base=2333,maxn=100005;
 10 unsigned long long tim[maxn];char s[maxn];
 11 struct node
 12 {
 13     int size,num;unsigned long long Has;
 14     node *ch[2],*pa;
 15     node(int has);
 16     int islc(){return ls(pa)==this;}
 17     void maintain();
 18 }*null=new node(0),*root=null;
 19 node::node(int has)
 20 {
 21     ch[0]=ch[1]=pa=null;
 22     num=Has=has;size=has?1:0;
 23 }
 24 void node::maintain()
 25 {
 26     size=ch[0]->size+ch[1]->size+1;
 27     Has=ch[0]->Has*tim[ch[1]->size+1]+num*tim[ch[1]->size]+ch[1]->Has;
 28 }
 29 void Rotate(node* rt,int d)
 30 {
 31     node *t=rt->ch[d^1];
 32     if(rt->pa!=null)rt->pa->ch[rt->islc()^1]=t;else root=t;
 33     t->pa=rt->pa;
 34     rt->ch[d^1]=t->ch[d];
 35     if(t->ch[d]!=null)t->ch[d]->pa=rt;
 36     t->ch[d]=rt,rt->pa=t;
 37     rt->maintain();t->maintain();
 38 }
 39 void Splay(node* x,node *tar)
 40 {
 41     for(node *rt=x->pa;rt!=tar;rt=x->pa)
 42     {
 43         if(rt->pa==tar){Rotate(rt,x->islc());break;}
 44         if(x->islc()==rt->islc())Rotate(rt->pa,x->islc());
 45         else Rotate(rt,x->islc());
 46         Rotate(x->pa,x->islc());
 47     }
 48     x->maintain();
 49 }
 50 void find(node *rt,int val,node *tar)
 51 {
 52     for(;;)
 53     {
 54         if(val<=ls(rt)->size)rt=ls(rt);
 55         else
 56         {
 57             val-=ls(rt)->size;
 58             if(val==1)break;
 59             val--,rt=rs(rt);
 60         }
 61     }
 62     Splay(rt,tar);
 63 }
 64 void build(node* &x,int l,int r)
 65 {
 66     if(l>r)return ;
 67     int mid=(l+r)>>1;x=new node(s[mid]-‘a‘+1);
 68     build(x->ch[0],l,mid-1),build(x->ch[1],mid+1,r);
 69     x->ch[0]->pa=x,x->ch[1]->pa=x;x->maintain();
 70 }
 71 void init()
 72 {
 73     tim[0]=1;
 74     for(int i=1;i<=100001;i++)tim[i]=tim[i-1]*base;
 75     scanf("%s",s);root=new node(20010117),root->ch[1]=new node(20010117);
 76     build(root->ch[1]->ch[0],0,strlen(s)-1);
 77     root->ch[1]->ch[0]->pa=root->ch[1],root->ch[1]->pa=root;root->ch[1]->maintain(),root->maintain();
 78 }
 79 bool check(int x,int y,int val)
 80 {
 81     find(root,x,null);find(root,x+val+1,root);
 82     unsigned long long Has1=root->ch[1]->ch[0]->Has;
 83     find(root,y,null);find(root,y+val+1,root);
 84     unsigned long long Has2=root->ch[1]->ch[0]->Has;
 85     return Has1==Has2;
 86 }
 87 int Query(int x,int y)
 88 {
 89     int l=0,r=root->size-1-max(x,y),mid;
 90     while(l<=r)
 91     {
 92         mid=(l+r)>>1;
 93         if(check(x,y,mid))l=mid+1;
 94         else r=mid-1;
 95     }
 96     return r;
 97 }
 98 int haha()
 99 {
100     init();char s[5];
101     int m;scanf("%d",&m);
102     while(m--)
103     {
104         scanf("%s",s);int x,y;
105         switch(s[0])
106         {
107             case ‘R‘:scanf("%d%s",&x,s);
108                     find(root,x+1,null);
109                     root->num=s[0]-‘a‘+1;root->maintain();break;
110             case ‘I‘:scanf("%d%s",&x,s);
111                     find(root,x+1,null);find(root,x+2,root);
112                     root->ch[1]->ch[0]=new node(s[0]-‘a‘+1),root->ch[1]->ch[0]->pa=root->ch[1];root->ch[1]->maintain();root->maintain();break;
113             default:scanf("%d%d",&x,&y);printf("%d\n",Query(x,y));
114         }
115     }
116 }
117 int sb=haha();
118 int main(){;}

bzoj1014