A - Musical Theme + 二分

 #include <bits/stdc++.h>
 using namespace std;

 #define LS 2*i
 #define RS 2*i+1
 #define UP(i,x,y) for(i=x;i<=y;i++)
 #define DOWN(i,x,y) for(i=x;i>=y;i--)
 #define MEM(a,x) memset(a,x,sizeof(a))
 #define W(a) while(a)
 #define gcd(a,b) __gcd(a,b)
 #define LL long long
 #define N 20005
 #define MOD 1000000007
 #define INF 0x3f3f3f3f
 #define EXP 1e-8
 int wa[N],wb[N],wsf[N],wv[N],sa[N];
 int rank1[N],height[N],s[N],a[N],n;
 char str1[N],str2[N];
 //sa:字典序中排第i位的起始位置在str中第sa[i]
 //rank:就是str第i个位置的后缀是在字典序排第几
 //height：字典序排i和i-1的后缀的最长公共前缀
 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)//n要包含末尾添加的0
 {
     int i,j,p,*x=wa,*y=wb,*t;
     for(i=; i<m; i++)  wsf[i]=;
     for(i=; i<n; i++)  wsf[x[i]=r[i]]++;
     for(i=; i<m; i++)  wsf[i]+=wsf[i-];
     for(i=n-; i>=; i--)  sa[--wsf[x[i]]]=i;
     p=;
     j=;
     for(; p<n; j*=,m=p)
     {
         for(p=,i=n-j; i<n; i++)  y[p++]=i;
         for(i=; i<n; i++)  if(sa[i]>=j)  y[p++]=sa[i]-j;
         for(i=; i<n; i++)  wv[i]=x[y[i]];
         for(i=; i<m; i++)  wsf[i]=;
         for(i=; i<n; i++)  wsf[wv[i]]++;
         for(i=; i<m; i++)  wsf[i]+=wsf[i-];
         for(i=n-; i>=; i--)  sa[--wsf[wv[i]]]=y[i];
         t=x;
         x=y;
         y=t;
         x[sa[]]=;
         for(p=,i=; i<n; i++)
             x[sa[i]]=cmp(y,sa[i-],sa[i],j)? p-:p++;
     }
 }
 void getheight(int *r,int n)//n不保存最后的0
 {
     int i,j,k=;
     for(i=; i<=n; i++)  rank1[sa[i]]=i;
     for(i=; i<n; i++)
     {
         if(k)
             k--;
         else
             k=;
         j=sa[rank1[i]-];
         while(r[i+k]==r[j+k])
             k++;
         height[rank1[i]]=k;
     }
 }
 int ans;
 int fun(int k)
 {
     int i,maxn,minn;
     maxn = minn = sa[];
     UP(i,,n)
     {
         if(height[i]>=k && i<n)
         {
             minn = min(minn,sa[i]);
             maxn = max(maxn,sa[i]);
             continue;
         }
         if(maxn-minn>=k) return ;
         maxn = minn = sa[i];
     }
     return ;
 }

 int main()
 {
     int i,j,k;
     W((~scanf("%d",&n),n))
     {
         UP(i,,n-)
         {
             scanf("%d",&s[i]);
         }
         UP(i,,n-)
         {
             s[i] = s[i+]-s[i]+;
         }
         s[--n] = ;
         getsa(s,sa,n+,);
         getheight(s,n);
         int l = ,r = n;
         W(l<=r)
         {
             int mid = (l+r)/;
             if(fun(mid))
             {
                 ans = mid;
                 l=mid+;
             }
             else r = mid-;
         }
         ans++;
         printf("%d\n",ans<?:ans);
     }

     return ;
 }