HUST 1352 Repetitions of Substrings(字符串)

Repetitions of Substrings

Description

The “repetitions” of a string S(whose length is n) is a maximum number “k” such that: 1) k is a factor of n 2) S[0..n/k-1] = S[p*(n/k)..(p+1)*(n/k)-1] for all that (1 <= p < n/k) for example: the repetitions of “aaaaaa”is 6. the repetitions of “abababab”is 4. the repetitions of “abcdef”is 1. Now, given a string S and a number K, please tell me how many substrings of S have repetitions NOT less than K.

Input

The input consists of several instances, each one for a single line. S K S is a string, K is a number. Check the Description for their meanings. S contains lowercase letters(ie 'a'..'z') only. 1 <= length of S <= 100000. 1 <= K <= length of S.

Output

For each instance, output the number of substring whose repetitions is NOT less than K.

Sample Input

abcabc 2
acmac 3

Sample Output

1
0

先记录一下，完全不知道怎么回事。

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <time.h>
using namespace std;
const int maxn=;
int height[maxn],sa[maxn],rank[maxn],c[maxn],t1[maxn],t2[maxn];
void da(int *str,int n,int m)
{
      int i,j,k,p,*x=t1,*y=t2;
      for(i=;i<m;i++)c[i]=;
      for(i=;i<n;i++)c[x[i]=str[i]]++;
      for(i=;i<m;i++)c[i]+=c[i-];
      for(i=n-;i>=;i--)sa[--c[x[i]]]=i;
      for(k=;k<=n;k<<=)
      {
         p=;
         for(i=n-k;i<n;i++)y[p++]=i;
         for(i=;i<n;i++)if(sa[i]>=k)y[p++]=sa[i]-k;
         for(i=;i<m;i++)c[i]=;
         for(i=;i<n;i++)c[x[y[i]]]++;
         for(i=;i<m;i++)c[i]+=c[i-];
         for(i=n-;i>=;i--)sa[--c[x[y[i]]]]=y[i];
         swap(x,y);
         p=;x[sa[]]=;
         for(i=;i<n;i++)
         x[sa[i]]=y[sa[i]]==y[sa[i-]]&&y[sa[i]+k]==y[sa[i-]+k]?p-:p++;
         if(p>=n)break;
         m=p;
      }
}
void calheight(int *str,int n)
{
      int i,j,k=;
      for(i=;i<=n;i++)rank[sa[i]]=i;
      for(i=;i<n;i++)
      {
         if(k)k--;
         j=sa[rank[i]-];
         while(str[i+k]==str[j+k])k++;
         height[rank[i]]=k;
      }
         // printf("sa:");for(i=0;i<=n;i++)printf("%d ",sa[i]);puts("");
         // printf("rank:");for(i=0;i<=n;i++)printf("%d ",rank[i]);puts("");
         // printf("height:");for(i=0;i<=n;i++)printf("%d ",height[i]);puts("");    

}
int str[maxn];
char ss[maxn];
int Log[maxn];
int best[][maxn];
void init(int n)
{
      int i,j;
      Log[]=-;
      for(i=;i<=n;i++)
         Log[i]=(i&(i-))?Log[i-]:Log[i-]+;
      for(i=;i<=n;i++)best[][i]=height[i];
      for(i=;i<=Log[n];i++)
         for(j=;j<=n;j++)
            best[i][j]=min(best[i-][j],best[i-][j+(<<(i-))]);
}
int lcp(int a,int b)
{
      a=rank[a];
      b=rank[b];
      if(a>b)swap(a,b);
      a++;
      int t=Log[b-a+];
      return min(best[t][a],best[t][b-(<<t)+]);
}
int rep[maxn];
int main()
{
      //freopen("data.in","r",stdin);
      //freopen("data.out","w",stdout);
      int i,j,k,m,n,p;
      while(~scanf("%s%d",&ss,&k))
      {
         n=strlen(ss);
           if(k==)
         {
            printf("%lld\n",(long long)n*(n+)/);
            continue;
         }
         for(i=;i<n;i++)str[i]=ss[i];
         str[n]=;
         da(str,n+,);
         calheight(str,n);
         init(n);
         for(i=;i<=n;i++)rep[i]=;
         for(int L=;L*k<=n;L++)
         {
            for(i=;i<n;i+=L)
            {
               int t=lcp(i,i+L);
               if(!t)continue;
               j=;
               while(j<=i&&j<L&&str[i-j]==str[i-j+L])
               {
                  if(t>=L&&lcp(i-j,i-j+L)>=(k-)*L)
                     rep[i-j]=max(rep[i-j],t/L+);
                  j++;t++;
               }
            }
         }
         int ans=;
         for(i=;i<=n;i++)if(rep[i]>=k)ans+=rep[i]-k+;
         printf("%d\n",ans);
      }
      return ;
}