题解:
用splay维护添加修改操作,然后二分hash判断长度.
操作一:对于查询区间[l,r]的hash值,显然将l-1旋到根,将r+1旋到根的右儿子,此时所求区间就是根的右儿子的左儿子了.
操作二:将要修改的位置旋到根,然后直接改就可以了.
操作三:要在x后面添加一个字符,显然将x旋到根,x+1旋到根的右儿子,然后直接加在根的右儿子的左儿子上就可以了.
1 #include<iostream> 2 #include<cstdlib> 3 #include<cstdio> 4 #include<cmath> 5 #include<algorithm> 6 #include<cstring> 7 #include<queue> 8 #include<vector> 9 #include<set> 10 #define MAXN 500010 11 #define RG register 12 #define LL long long int 13 using namespace std; 14 const int INF=1e9; 15 const int mod=9875321; 16 int ch[MAXN][2],siz[MAXN],v[MAXN],ha[MAXN],fa[MAXN]; 17 int p[MAXN]; 18 int n,m,root,sz; 19 int val[MAXN]; 20 char s[MAXN]; 21 void up(int x) 22 { 23 int l=ch[x][0],r=ch[x][1]; 24 siz[x]=siz[l]+siz[r]+1; 25 ha[x]=(ha[l]+v[x]*p[siz[l]]%mod+(LL)ha[r]*p[siz[l]+1]%mod)%mod; 26 } 27 void build(int &k,int l,int r,int f) 28 { 29 if(l>r) return; 30 int mid=(l+r)>>1; 31 k=++sz;fa[k]=f;v[k]=val[mid]; 32 if(mid>l) build(ch[k][0],l,mid-1,k); 33 if(mid<r) build(ch[k][1],mid+1,r,k); 34 up(k); 35 } 36 void rotate(int x,int &k) 37 { 38 int old=fa[x],oldf=fa[old],rel=(ch[old][1]==x); 39 if(old==k) k=x; 40 else ch[oldf][ch[oldf][1]==old]=x; 41 fa[x]=oldf;fa[ch[x][rel^1]]=old;ch[old][rel]=ch[x][rel^1]; 42 fa[old]=x;ch[x][rel^1]=old; 43 up(old);up(x); 44 } 45 void splay(int x,int &k) 46 { 47 int old,oldf; 48 while(x!=k) 49 { 50 old=fa[x];oldf=fa[old]; 51 if(old!=k) 52 { 53 if((ch[old][0]==x)^(ch[oldf][0]==old)) rotate(x,k); 54 else rotate(old,k); 55 } 56 rotate(x,k); 57 } 58 } 59 int find(int x) 60 { 61 int now=root; 62 while(1) 63 { 64 if(x<=siz[ch[now][0]]) now=ch[now][0]; 65 else{ 66 if(x==siz[ch[now][0]]+1) return now; 67 x-=siz[ch[now][0]]+1;now=ch[now][1]; 68 } 69 } 70 } 71 void change(int x,char d) 72 { 73 x=find(x);splay(x,root); 74 v[root]=d-‘a‘+1;up(root); 75 } 76 void insert(int x,char d) 77 { 78 int l=x,r=x+1; 79 l=find(l);r=find(r);splay(l,root);splay(r,ch[root][1]); 80 ++sz;ch[r][0]=sz;v[sz]=d-‘a‘+1;fa[sz]=r;up(sz);up(r);up(l); 81 } 82 int get(int x,int y) 83 { 84 x=find(x-1);y=find(y+1); 85 splay(x,root);splay(y,ch[root][1]); 86 return ha[ch[y][0]]; 87 } 88 int solve(int x,int y) 89 { 90 int l=1,r=min(sz-x,sz-y),ans=0; 91 while(l<=r) 92 { 93 int mid=(l+r)>>1; 94 if(get(x,x+mid-1)==get(y,y+mid-1)) ans=mid,l=mid+1; 95 else r=mid-1; 96 } 97 return ans; 98 } 99 int main() 100 { 101 freopen("1.in","r",stdin); 102 scanf("%s",s);n=strlen(s);p[0]=1; 103 for(int i=1;i<=150010;i++) p[i]=p[i-1]*28%mod; 104 for(int i=1;i<=n+2;i++) if(i==1 || i== n+2) val[i]=27; else val[i]=s[i-2]-‘a‘+1; 105 build(root,1,n+2,0); 106 scanf("%d",&m);char op[3],d[3];int x,y; 107 for(int i=1;i<=m;i++) 108 { 109 scanf("%s%d",op,&x);x++; 110 if(op[0]==‘Q‘){ 111 scanf("%d",&y);y++; 112 printf("%d\n",solve(x,y)); 113 } 114 if(op[0]==‘R‘){ 115 scanf("%s",d);change(x,d[0]); 116 } 117 if(op[0]==‘I‘){ 118 scanf("%s",d);insert(x,d[0]); 119 } 120 } 121 return 0; 122 }
