#include<cstdio>
#include<cstring>
using namespace std;
typedef int aa[30000];
aa a,ws,wb,wa,sa,ra,wv,Height,h;
int n;
void init()
{
	memset(sa,0,sizeof(sa));
	memset(ra,0,sizeof(ra));
	for (int i=0;i<n;++i)
		scanf("%d",&a[i]);
	for (int i=0;i<n-1;++i) a[i]=a[i+1]-a[i]+100;
	a[n-1]=0;
}
bool cmp(int *r,int i, int j, int k)
{
	return r[i]==r[j]&&r[i+k]==r[j+k];
}
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) ws[i]=0;
	for (i=0;i<n;++i) ws[x[i]=r[i]]++;
	for (i=1;i<m;++i) ws[i]+=ws[i-1];
	for (i=n-1;i>=0;--i) sa[--ws[x[i]]]=i;
	for (j=1,p=1;p<n;j=j<<1,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<m;++i) ws[i]=0;
		for (i=0;i<n;++i) wv[i]=x[y[i]];
		for (i=0;i<n;++i) ws[wv[i]]++;
		for (i=1;i<m;++i) ws[i]+=ws[i-1];
		for (i=n-1;i>=0;--i) sa[--ws[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++;
	}
}
void calHeight(int *r,int n)
{
	int i=0,j,p=0;
	for (i=0;i<n;++i) ra[sa[i]]=i;
	for (i=0;i<n;Height[ra[i++]]=p)
		for (p?p--:0,j=sa[ra[i]-1];r[j+p]==r[i+p];p++);
	memcpy(h,Height,sizeof(Height));
}
void prepare(int x)
{
	memcpy(Height,h,sizeof(h));
	for (int i=0;i<n;++i)
	{
		Height[i]-=x-1;
		if (Height[i]<0) Height[i]=0;
	}
}
void expand(int &min,int &max,int x)
{
	if (x>max) max=x;
	if (x<min) min=x;
}
bool check(int x)
{
	prepare(x);
	int min=1000000,max=0;
	for (int i=0;i<n;++i)
	{
		if (Height[i]==0) 
		{  
			if (max-min>x) return 1;
			min=1000000; max=0;
			continue;
		}
		expand(min,max,sa[i]);
		expand(min,max,sa[i-1]);
	}
	if (max-min>x) return 1;
	return 0;
}
void solve()
{
	da(a,sa,n,300);
	calHeight(a,n);
	int l=0,r=n;
	while (l+1<r)
	{
		int mid=(l+r)/2;
		if (check(mid)) l=mid;
		else r=mid;
	}
	if (l+1<5) printf("0\n");
	else printf("%d\n",l+1);
}
int main()
{
	scanf("%d",&n);
	while (n!=0)
	{
		init();	
		if (n==1) printf("0\n"); //****************
		else solve();
		scanf("%d",&n);
	}
	return 0;
}

• Re:巨坑！大家亲注意n=1时的情况。。。。否则无限RE (13) dong_123 2013-04-01 15:40:45
• Re:巨坑！大家亲注意n=1时的情况。。。。否则无限RE (11) SCQ 2013-04-27 20:39:35
• Re:巨坑！大家亲注意n=1时的情况。。。。否则无限RE (2310) wuhoudewutongyu 2013-04-27 22:18:17
  • Re:巨坑！大家亲注意n=1时的情况。。。。否则无限RE (7) moya_hy 2013-09-01 19:11:40
    • Re:巨坑！大家亲注意n=1时的情况。。。。否则无限RE (4) liucy1998 2017-10-06 15:54:36