hdu 4691 Front compression (基于hash的LCP)

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题目：http://acm.hdu.edu.cn/showproblem.php?pid=4691

题意：

分析：直接求LCP啊。。。

代码：

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;typedef unsigned long long ULL;const int maxn = 1e5+6;const int seed = 131;ULL H[maxn],X[maxn];int Len;char str[maxn];void Init(){H[Len]=0;for(int i=Len-1;i>=0;i--)H[i]=H[i+1]*seed+str[i]-'a';X[0]=1;for(int i=1;i<Len;i++)X[i]=X[i-1]*seed;}ULL GetHash(int i,int L){return H[i]-H[i+L]*X[L];}int LCP(int a,int b,int lim){int ret=0,down=1,mid,up=lim;while(down<=up){mid=(down+up)>>1;if(GetHash(a,mid)==GetHash(b,mid)){down=mid+1;if(ret<mid)ret=mid;}elseup=mid-1;}return ret;}int GetLen(int x){if(x==0)return 1;int ret=0;while(x){ret++;x/=10;}return ret;}int main(){int i,j,Q,a,b,lim,pera,perb,f;long long in,ou;while(scanf("%s",str)!=EOF){Len=strlen(str);Init();scanf("%d",&Q);scanf("%d%d",&pera,&perb);in=perb-pera+1;ou=3+perb-pera;Q--;while(Q--){scanf("%d%d",&a,&b);in+=b-a+1;lim=min(perb-pera,b-a);f=LCP(pera,a,lim);ou+=GetLen(f)+1+(b-a-f)+1;pera=a;perb=b;}printf("%I64d %I64d\n",in,ou);}return 0;}

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