HDU2459[Maximum repetition substring]

 1 #include<map>
 2 #include<set>
 3 #include<list>
 4 #include<deque>
 5 #include<cmath>
 6 #include<queue>
 7 #include<stack>
 8 #include<vector>
 9 #include<cstdio>
10 #include<complex>
11 #include<cstring>
12 #include<cstdlib>
13 #include<iostream>
14 #include<algorithm>
15 #define maxx 100010
16 using namespace std;
17 int X[maxx],Y[maxx],sa[maxx],height[maxx],rnk[maxx],tong[maxx];
18 char s[maxx];int num[maxx];
19 bool comp(int *r,int a,int b,int len){return r[a]==r[b]&&r[a+len]==r[b+len];}
20 void build_sa(int n){
21   int *x=X,*y=Y,*t,Max=200;
22   for(int i=0;i<=Max;++i)tong[i]=0;
23   for(int i=0;i<n;++i)tong[x[i]=num[i]]++;
24   for(int i=1;i<=Max;++i)tong[i]+=tong[i-1];
25   for(int i=n-1;i!=-1;i--)sa[--tong[x[i]]]=i;
26   for(int j=1,p=0,i;p<n;Max=p,j<<=1){
27     for(i=n-1,p=0;i>=n-j;--i)y[p++]=i;
28     for(i=0;i<n;++i)if(sa[i]>=j)y[p++]=sa[i]-j;
29     for(i=0;i<=Max;++i)tong[i]=0;
30     for(i=0;i<n;++i)tong[x[y[i]]]++;
31     for(i=1;i<=Max;++i)tong[i]+=tong[i-1];
32     for(i=n-1;i!=-1;i--)sa[--tong[x[y[i]]]]=y[i];
33     for(t=x,x=y,y=t,x[sa[0]]=0,p=1,i=1;i<n;++i)
34       x[sa[i]]=comp(y,sa[i],sa[i-1],j)?p-1:p++;
35   }
36 }int n;
37 void geth(){int i,j,k=0;
38   for(i=1;i<=n;++i)rnk[sa[i]]=i;
39   for(i=0;i<n;height[rnk[i++]]=k)
40     for(k?k--:0,j=sa[rnk[i]-1];num[j+k]==num[i+k];k++);
41 }
42 int dp[maxx][19];
43 void RMQ(){
44   for(int i=1;i<=n;++i)dp[i][0]=height[i];
45   for(int j=1;(1<<j)<=n;++j)
46     for(int i=1;i+(1<<(j-1))<n;++i)
47       dp[i][j]=min(dp[i][j-1],dp[i+(1<<(j-1))][j-1]);
48 }
49 LL LCP(int x,int y){
50   x=rnk[x],y=rnk[y];if(x>y)swap(x,y);x++;
51   int t=(int)(log(double(y-x+1))/log(2.000));
52   return min(dp[x][t],dp[y-(1<<t)+1][t]);
53 }
54 int main(){
55   freopen("1.in","r",stdin);
56   freopen("1.out","w",stdout);int T=1;
57   while(scanf("%s",s)&&s[0]!=‘#‘){int ans=0;
58     cout<<"Case "<<T<<": ";T++;
59     memset(X,0,sizeof(X));
60     memset(Y,0,sizeof(Y));
61     memset(sa,0,sizeof(sa));
62     memset(height,0,sizeof(height));
63     memset(rnk,0,sizeof(rnk));n=strlen(s);
64     for(int i=0;i<n;++i)num[i]=s[i]-90;num[n]=0;
65     build_sa(n+1),geth(),RMQ();int P,pos,nu,cnt,len,t;
66     for(int i=1;i<=(n>>1);++i)
67       for(int j=0;j+i<n;j+=i){
68     if(num[j]!=num[j+i])continue;
69     int L=LCP(j,j+i);
70     nu=L/i+1;pos=j;
71     t=i-L%i;cnt=0;
72     for(int k=j-1;k>=0&&k+i>j&&num[k]==num[k+i];k--){
73       cnt++;
74       if(cnt==t)nu++,pos=k;
75       else if(rnk[k]<rnk[pos])pos=k;
76     }
77     if(ans<nu)ans=nu,P=pos,len=i;
78     else if(rnk[P]>rnk[pos]&&ans==nu)P=pos,len=i;
79       }
80     for(int i=P;i<P+ans*len;++i)cout<<s[i];
81     cout<<‘\n‘;
82   }
83   return 0;
84 }