【POJ1743】不可重叠最长重复子串

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iostream>
using namespace std;

int sa[20010],rank[20010],y[20010],Rsort[20010];
int wr[20010],a[20010],height[20010],n;

bool cmp(int k1,int k2,int ln){return wr[k1]==wr[k2] && wr[k1+ln]==wr[k2+ln];}

void get_sa(int m)
{
int i,k,p,ln;

memcpy(rank,a,sizeof(rank));

memset(Rsort,0,sizeof(Rsort));
for (i=1;i<=n;i++) Rsort[rank[i]]++;
for (i=1;i<=m;i++) Rsort[i]+=Rsort[i-1];
for (i=n;i>=1;i--) sa[Rsort[rank[i]]--]=i;

ln=1; p=0;
while (p<n)
{
for (k=0,i=n-ln+1;i<=n;i++) y[++k]=i;
for (i=1;i<=n;i++) if (sa[i]>ln) y[++k]=sa[i]-ln;
for (i=1;i<=n;i++) wr[i]=rank[y[i]];

memset(Rsort,0,sizeof(Rsort));
for (i=1;i<=n;i++) Rsort[wr[i]]++;
for (i=1;i<=m;i++) Rsort[i]+=Rsort[i-1];
for (i=n;i>=1;i--) sa[Rsort[wr[i]]--]=y[i];

memcpy(wr,rank,sizeof(wr));
p=1; rank[sa[1]]=1;
for (i=2;i<=n;i++)
{
if (!cmp(sa[i],sa[i-1],ln)) p++;
rank[sa[i]]=p;
}
m=p; ln*=2;
}
a[0]=sa[0]=0;
}

void get_he()
{
int i,j,k=0;
for (i=1;i<=n;i++)
{
j=sa[rank[i]-1];
if (k) k--;

while (a[j+k]==a[i+k]) k++;
height[rank[i]]=k;
}
}

bool check(int k)
{
int i,maxx=0,minn=20010;
for(i=1;i<=n;i++)
{
if(height[i]<k) maxx=minn=sa[i];
else
{
if(sa[i]>maxx) maxx=sa[i];
if(sa[i]<minn) minn=sa[i];
if(maxx-minn>k) return 1;
}
}
return 0;
}

int hd_work()
{
int l,r,mid,ans=0;
l=1;r=n;
while(l<=r)
{
mid=(l+r)/2;
if(check(mid))
{
l=mid+1;
ans=mid;
}
else r=mid-1;
}
if(ans>=4) ans++;
else ans=0;
return ans;
}

int main()
{
int i,a1,a2;
while(1)
{
scanf("%d",&n);
if(n==0) break;
scanf("%d",&a1);
for(i=2;i<=n;i++)
{
scanf("%d",&a2);
a[i-1]=a2-a1+88;
a1=a2;
}
n--;
get_sa(20010);
get_he();
printf("%d\n",hd_work());
}
}