[JSOI2008]火星人 hash+splay

Posted 2021-01-16 EM-LGH

Code:

#include<cstdio>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<string>
const int maxm=3000000;
const int maxn=3000000; 
using namespace std;
void setIO(string a){
	freopen((a+".in").c_str(),"r",stdin);
}
void debug(){
	printf("ok
");
}
char str[maxn];
unsigned int hash[maxm],p[maxm];
int n,root;
struct Splay_Tree{
	int ch[maxn][2],cnt_Tree,f[maxn],key[maxn],siz[maxn];
	#define lson ch[o][0]
	#define rson ch[o][1]
	int newnode(){return ++cnt_Tree;}
	int get(int x){return ch[f[x]][1]==x;}
    void pushup(int o){
    	if(!o) return ;
	    siz[o]=siz[lson]+siz[rson]+1;
	    hash[o]=hash[lson]+key[o]*p[siz[lson]]+hash[rson]*p[siz[lson]+1];
    }
    void buildSplay(int l,int r,int fa,int &o){
	    if(l>r) return;
	    int mid=(l+r)>>1;
	    o=newnode();
	    hash[o]=key[o]=str[mid]-‘a‘;
	    f[o]=fa;  
	    buildSplay(l,mid-1,o,ch[o][0]);
	    buildSplay(mid+1,r,o,ch[o][1]);
	    pushup(o);
    }
    void rotate(int x){
	    int old=f[x],oldf=f[old],which=get(x);
	    ch[old][which]=ch[x][which^1],f[ch[old][which]]=old;
	    ch[x][which^1]=old,f[old]=x;
	    f[x]=oldf;
	    if(oldf)
	    	ch[oldf][ch[oldf][1]==old]=x;
	    pushup(old),pushup(x);
	}
	void splay(int x,int &tar){
		int a=f[tar];
		for(int fa;(fa=f[x])!=a;rotate(x))
			if(f[fa]!=a) rotate(get(fa)==get(x)?fa:x);
		tar=x;
	}
	int findx(int pos,int o){                         //accurate position
		if(pos<=siz[ch[o][0]]) return findx(pos,ch[o][0]);
		else if(pos==siz[lson]+1) return o;
		else return findx(pos-siz[ch[o][0]]-1,ch[o][1]);
	}
	void insert(int pos,int val){
		int x=findx(pos,root);
		splay(x,root);
		int y=findx(pos+1,root);
		splay(y,ch[root][1]);
		int z=ch[ch[root][1]][0]=newnode();           //between
		f[z]=ch[root][1];
		hash[z]=key[z]=val;
		pushup(z),pushup(ch[root][1]);
		splay(z,root);
	}
	void update(int pos,int val){
		splay(findx(pos,root),root);
		key[root]=hash[root]=val;
		pushup(root);
	}
	unsigned int query(int pos,int length){
		int x=findx(pos-1,root);                     //origin
		splay(x,root);
		int y=findx(length+1,ch[root][1]);
		splay(y,ch[root][1]);                        //error!!!!
		int tmp=ch[root][1];
		return hash[ch[tmp][0]];
	}
}T;
void init(){
	scanf("%s",str+2);
	n=strlen(str+2);
	str[n+2]=‘a‘;
	str[1]=‘a‘;
	n+=2;
	p[0]=1;
	for(int i=1;i<maxn;++i) p[i]=p[i-1]*27;
}
int main(){
	//setIO("input");
	init();
	T.buildSplay(1,n,0,root);
	int m; 
	scanf("%d",&m);
	while(m--){
		char opt[10];
		scanf("%s",opt);
		if(opt[0]==‘Q‘){
			int a,b;
			scanf("%d%d",&a,&b);
			if(a>b) swap(a,b);
			++a,++b;                            
			int l=1,r=n-b,ans=0;                    
			while(l<=r){
				int mid=(l+r)>>1;
				if(T.query(a,mid)==T.query(b,mid)) ans=mid,l=mid+1;
				else r=mid-1;
			}
			printf("%d
",ans);
			continue;
		}
		char ss[10];
		int x,delta;
		scanf("%d",&x);
		scanf("%s",ss);
		delta=ss[0]-‘a‘;
		if(opt[0]==‘I‘) T.insert(x+1,delta),n+=1;			     //insert position: x+2 -> x+2
		if(opt[0]==‘R‘) T.update(x+1,delta);                     //actual position: x+1 
	}
	return 0;
}