694. Distinct Substrings (后缀数组)

694. Distinct Substrings

Problem code: DISUBSTR

http://www.spoj.com/problems/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;
}