694. Distinct Substrings (后缀数组)
694. Distinct SubstringsProblem code: DISUBSTR |
Given a string, we need to find the total number of its distinct substrings.
Input
T- number of test cases. T<=20;
Each test case consists of one string, whose length is <= 1000
Output
For each test case output one number saying the number of distinct substrings.
Example
Sample Input:
2
CCCCC
ABABA
Sample Output:
5
9
Explanation for the testcase with string ABABA:
len=1 : A,B
len=2 : AB,BA
len=3 : ABA,BAB
len=4 : ABAB,BABA
len=5 : ABABA
Thus, total number of distinct substrings is 9.
这个超时,有待检查:
#include<iostream> #include<cstdio> #include<cstring> using namespace std; const int maxn=1010; char str[maxn]; int wa[maxn],wb[maxn],wv[maxn],wn[maxn],a[maxn],sa[maxn]; int cmp(int *r,int a,int b,int l){ return r[a]==r[b] && r[a+l]==r[b+l]; } void da(int *r,int *sa,int n,int m){ int i,j,p,*x=wa,*y=wb,*t; for(i=0; i<m; i++) wn[i]=0; for(i=0; i<n; i++) wn[x[i]=r[i]]++; for(i=1; i<m; i++) wn[i]+=wn[i-1]; for(i=n-1; i>=0; i--) sa[--wn[x[i]]]=i; for(j=1,p=1; p<n; j*=2,m=p){ for(p=0,i=n-j; i<n; i++) y[p++]=i; for(i=0; i<n; i++) if(sa[i]>=j) y[p++]=sa[i]-j; for(i=0; i<n; i++) wv[i]=x[y[i]]; for(i=0; i<m; i++) wn[wv[i]]++; for(i=1; i<m; i++) wn[i]+=wn[i-1]; for(i=n-1; i>=0; i--) sa[--wn[wv[i]]]=y[i]; for(t=x,x=y,y=t,p=1,x[sa[0]]=0,i=1; i<n; i++) x[sa[i]]=cmp(y,sa[i-1],sa[i],j)?p-1:p++; } } int rank[maxn],height[maxn]; void calheight(int *r,int *sa,int n){ int i,j,k=0; for(i=1; i<=n; i++) rank[sa[i]]=i; for(i=0; i<n; height[rank[i++]]=k) for(k?k--:0,j=sa[rank[i]-1]; r[i+k]==r[j+k]; k++); } int main(){ freopen("input.txt","r",stdin); int t; scanf("%d",&t); while(t--){ scanf("%s",str); int n=strlen(str); for(int i=0;i<n;i++) a[i]=(int)str[i]; a[n]=0; da(a,sa,n+1,260); calheight(a,sa,n); int sum=0; for(int i=1;i<=n;i++) sum+=n-sa[i]-height[i]; printf("%d\n",sum); } return 0; }
AC:http://www.cnblogs.com/kuangbin/archive/2013/04/24/3039634.html
#include<iostream> #include<cstdio> #include<cstring> using namespace std; const int maxn=1010; char str[maxn]; int wa[maxn],wb[maxn],wv[maxn],wn[maxn],a[maxn],sa[maxn]; int cmp(int *r,int a,int b,int l){ return r[a]==r[b] && r[a+l]==r[b+l]; } void da(int *r,int *sa,int n,int m){ int i,j,p,*x=wa,*y=wb,*t; for(i=0; i<m; i++) wn[i]=0; for(i=0; i<n; i++) wn[x[i]=r[i]]++; for(i=1; i<m; i++) wn[i]+=wn[i-1]; for(i=n-1; i>=0; i--) sa[--wn[x[i]]]=i; for(j=1,p=1; p<n; j*=2,m=p){ for(p=0,i=n-j; i<n; i++) y[p++]=i; for(i=0; i<n; i++) if(sa[i]>=j) y[p++]=sa[i]-j; for(i=0; i<n; i++) wv[i]=x[y[i]]; for(i=0; i<m; i++) wn[wv[i]]++; for(i=1; i<m; i++) wn[i]+=wn[i-1]; for(i=n-1; i>=0; i--) sa[--wn[wv[i]]]=y[i]; for(t=x,x=y,y=t,p=1,x[sa[0]]=0,i=1; i<n; i++) x[sa[i]]=cmp(y,sa[i-1],sa[i],j)?p-1:p++; } } int rank[maxn],height[maxn]; void calheight(int *r,int *sa,int n){ int i,j,k=0; for(i=1; i<=n; i++) rank[sa[i]]=i; for(i=0; i<n; height[rank[i++]]=k) for(k?k--:0,j=sa[rank[i]-1]; r[i+k]==r[j+k]; k++); } int main(){ freopen("input.txt","r",stdin); int t; scanf("%d",&t); while(t--){ scanf("%s",str); int n=strlen(str); for(int i=0;i<n;i++) a[i]=(int)str[i]; a[n]=0; da(a,sa,n+1,260); calheight(a,sa,n); int sum=0; for(int i=1;i<=n;i++) sum+=n-sa[i]-height[i]; printf("%d\n",sum); } return 0; }