POJ 1743 Musical Theme(后缀数组)

int r
,sa
,wa
,wb
,wd
,rank
,h
;

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;
FOR0(i,m) wd[i]=0;
FOR0(i,n) wd[x[i]=r[i]]++;
FOR1(i,m-1) wd[i]+=wd[i-1];
FORL0(i,n-1) sa[--wd[x[i]]]=i;
for(j=1,p=1;p<n;j<<=1,m=p)
{
p=0;
FOR(i,n-j,n-1) y[p++]=i;
FOR0(i,n) if(sa[i]>=j) y[p++]=sa[i]-j;
FOR0(i,m) wd[i]=0;
FOR0(i,n) wd[x[i]]++;
FOR1(i,m-1) wd[i]+=wd[i-1];
FORL0(i,n-1) sa[--wd[x[y[i]]]]=y[i];
t=x;x=y;y=t;p=1;x[sa[0]]=0;
FOR1(i,n-1) x[sa[i]]=cmp(y,sa[i-1],sa[i],j)?p-1:p++;
}
}

void calHeight(int *r,int *sa,int n)
{
int i,j,k=0;
FOR1(i,n) rank[sa[i]]=i;
FOR0(i,n)
{
if(k) k--;
j=sa[rank[i]-1];
while(i+k<n&&j+k<n&&r[i+k]==r[j+k]) k++;
h[rank[i]]=k;
}
}

int n;

int OK(int x)
{
int i=2,j,L,R,Max,Min;
while(i<=n)
{
L=i;
while(L<=n&&h[L]<x) L++;
R=L;
while(R+1<=n&&h[R+1]>=x) R++;
if(R>n) return 0;
Max=-INF,Min=INF;
FOR(j,L,R)
{
Max=max(Max,max(sa[j],sa[j-1]));
Min=min(Min,min(sa[j],sa[j-1]));
}
if(Max-Min>=x) return 1;
i=R+1;
}
return 0;
}

void cal()
{
int low=0,high=n,mid;
while(low<=high)
{
mid=(low+high)>>1;
if(OK(mid)) low=mid+1;
else high=mid-1;
}
int ans;
if(low<=n&&OK(low)) ans=low+1;
else ans=high+1;
if(ans<5) ans=0;
PR(ans);
}

int main()
{
while(scanf("%d",&n),n)
{
int i,pre,cur;
RD(pre);
FOR0(i,n-1) RD(cur),r[i]=cur-pre+100,pre=cur;
n--;
r
=0;
da(r,sa,n+1,200);
calHeight(r,sa,n);
cal();
}
return 0;
}