poj2774

题解：

后缀数组

把两个串合并起来

代码：

#include<algorithm>
#include<cmath>
#include<cstdio>
#include<cstring>
using namespace std;
const int N=200010;
int dp[N][33],wa[N],wb[N],wsf[N],wv[N],sa[N],rank[N],height[N],s[N];
char str[N],str1[N];
int cmp(int *r,int a,int b,int k)
{
    return r[a]==r[b]&&r[a+k]==r[b+k];
}
void getsa(int *r,int *sa,int n,int m)
{
    int *x=wa,*y=wb;
    for (int i=0;i<m;i++)wsf[i]=0;
    for (int i=0;i<n;i++)wsf[x[i]=r[i]]++;
    for (int i=1;i<m;i++)wsf[i]+=wsf[i-1];
    for (int i=n-1;i>=0;i--)sa[--wsf[x[i]]]=i;
    int p=1,j=1;
    for (;p<n;j*=2,m=p)
     {
         p=0;
        for (int i=n-j;i<n;i++)y[p++]=i;
        for (int i=0;i<n;i++)
         if (sa[i]>=j)y[p++]=sa[i]-j;
        for (int i=0;i<n;i++)wv[i]=x[y[i]];
        for (int i=0;i<m;i++)wsf[i]=0;
        for (int i=0;i<n;i++)wsf[wv[i]]++;
        for (int i=1;i<m;i++)wsf[i]+=wsf[i-1];
        for (int i=n-1;i>=0;i--)sa[--wsf[wv[i]]]=y[i];
        swap(x,y);
        x[sa[0]]=0;
        p=1;
        for (int i=1;i<n;i++)
         x[sa[i]]=cmp(y,sa[i-1],sa[i],j)? p-1:p++;
     }
}
void getheight(int *r,int n)
{
    int k=0;
    for (int i=1;i<=n;i++)rank[sa[i]]=i;
    for (int i=0;i<n;i++)
     {
        if (k)k--;
        int j=sa[rank[i]-1];
        while (r[i+k]==r[j+k])k++;
        height[rank[i]]=k;
    }
}
int main()
{
    while (~scanf("%s",str))
     {
        scanf("%s",str1);
        int n=0,len=strlen(str);
        for (int i=0;i<len;i++)s[n++]=str[i]-'a'+1;
        s[n++]=28;
        len=strlen(str1);
        for (int i=0;i<len;i++)s[n++]=str1[i]-'a'+1;
        s[n]=0;
        getsa(s,sa,n+1,30);
        getheight(s,n);
        int maxx=0,pos=0;
        len=strlen(str);
        for (int i=2;i<n;i++)
         if (height[i]>maxx)
          {
            if (0<=sa[i-1]&&sa[i-1]<len&&len<sa[i])
            maxx=height[i];
            if (0<=sa[i]&&sa[i]<len&&len<sa[i-1])
            maxx=height[i];
          }
        printf("%d\n",maxx);
     }
    return 0;
}