【BZOJ】【P2258】【pku2758 Checking the Text 文本校对】【题解】【hash】

来源：互联网发布：许佳琪吴哲晗吵架知乎编辑：程序博客网时间：2024/06/07 12:23

传送门:http://www.lydsy.com/JudgeOnline/problem.php?id=2258

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Code:

#include<cstdio>#include<cctype>#include<cstring>#include<iostream>#include<algorithm>using namespace std;const int maxn=50300;typedef unsigned long long UL;UL base=233;UL hash[maxn];UL hash_l[maxn];char s[maxn];int len,m;void hash_init(int be){UL val=hash[be-1];for(int i=be;i<=len;i++){val=val*base+s[i]-'a';hash[i]=val;}}int mp[maxn+200];int main(){scanf("%s",s+1);s[0]='#';len=strlen(s+1);hash_l[0]=1;for(int i=1;i<=len+200;i++)hash_l[i]=hash_l[i-1]*base,mp[i]=i;scanf("%d",&m);hash_init(1);while(m--){char op=getchar();while(op!='Q'&&op!='I')op=getchar();if(op=='I'){char x=getchar();while(!isalpha(x))x=getchar();int ps;scanf("%d",&ps);if(ps>len)ps=len+1;for(int i=len+1;i>ps;i--)s[i]=s[i-1];for(int j=lower_bound(mp+1,mp+1+len,ps)-mp,i=j;i<=len+1;i++)mp[i]++;s[ps]=x;len++;s[len+1]='\0';hash_init(ps);}else{int a,b;scanf("%d%d",&a,&b);a=mp[a];b=mp[b];int l=0,r=len-b+2;while(l<r){int mid=(l+r)>>1;if(hash[a+mid-1]-hash[a-1]*hash_l[mid]==hash[b+mid-1]-hash[b-1]*hash_l[mid])l=mid+1;else r=mid;}printf("%d\n",l-1);}}return 0;}

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