Poj 1226 substrings (suffix array)

Question:

This is a substring that appears in all M strings. The substring can also appear in the reverse sequence of the substring.

Train of Thought Analysis:

Actually Wa has five "A" data records.

The lower bound cannot be 0 in binary mode ..

In general, the idea is to process all the original and reverse strings, put them in STR, and then add one between each string that has not appeared.

Note that the input is not just a letter.

Run the suffix array again.

Then, use the mark to count.

#include <iostream>#include <cstdio>#include <algorithm>#include <cstring>#include <cmath>#define maxn 100005using namespace std;int str[maxn];int sa[maxn],t1[maxn],t2[maxn],c[maxn],n;void suffix(int m){    int *x=t1,*y=t2;    for(int i=0; i<m; i++)c[i]=0;    for(int i=0; i<n; i++)c[x[i]=str[i]]++;    for(int i=1; i<m; i++)c[i]+=c[i-1];    for(int i=n-1; i>=0; i--)sa[--c[x[i]]]=i;    for(int k=1; k<=n; k<<=1)    {        int p=0;        for(int i=n-k; i<n; i++)y[p++]=i;        for(int i=0; i<n; i++)if(sa[i]>=k)y[p++]=sa[i]-k;        for(int i=0; i<m; i++)c[i]=0;        for(int i=0; i<n; i++)c[x[y[i]]]++;        for(int i=0; i<m; i++)c[i]+=c[i-1];        for(int i=n-1; i>=0; i--)sa[--c[x[y[i]]]]=y[i];        swap(x,y);        p=1;        x[sa[0]]=0;        for(int i=1; i<n; i++)            x[sa[i]]=y[sa[i-1]]==y[sa[i]]&&y[sa[i-1]+k]==y[sa[i]+k]?p-1:p++;        if(p>=n)break;        m=p;    }}int rank[maxn],height[maxn];void getheight(){    int k=0;    for(int i=0; i<n; i++)rank[sa[i]]=i;    for(int i=0; i<n; i++)    {        if(k)k--;        if(!rank[i])continue;        int j=sa[rank[i]-1];        while(str[i+k]==str[j+k])k++;        height[rank[i]]=k;    }}char tmp[105];bool vis[105];int dex[maxn];bool check(int len,int m){    int cnt=m;    memset(vis,false,sizeof vis);    for(int i=1;i<n;i++)    {        if(height[i]<len)        {            if(!cnt)return true;            cnt=m;            memset(vis,false,sizeof vis);        }        else        {            if(!vis[dex[sa[i-1]]])            {                cnt--;                vis[dex[sa[i-1]]]=true;            }            if(!vis[dex[sa[i]]])            {                cnt--;                vis[dex[sa[i]]]=true;            }        }    }    return false;}int main(){    int T;    scanf("%d",&T);    while(T--)    {        n=0;        int m;        scanf("%d",&m);        for(int i=1;i<=m;i++)        {            scanf("%s",tmp);            int len=strlen(tmp);            for(int j=0;j<len;j++)            {                dex[n]=i;                str[n++]=tmp[j];            }            dex[n]=i;            str[n++]=128+i*2-1;            reverse(tmp,tmp+len);            for(int j=0;j<len;j++)            {                dex[n]=i;                str[n++]=tmp[j];            }            dex[n]=i;            str[n++]=128+i*2;        }        str[n-1]=0;        suffix(400);        getheight();        int l=1,r=100,ans=0;        while(l<=r)        {            int mid=(l+r)>>1;            if(check(mid,m))            ans=mid,l=mid+1;            else r=mid-1;        }        printf("%d\n",ans);    }    return 0;}