学步园

Description

Input

Output

Sample Input

8 2
1
2
3
2
3
2
3
1

Sample Output

4

/************************************************************************</p> <p> 后缀数组 + 二分枚举答案（判断条件是出现至少k次）</p> <p>************************************************************************/</p> <p>#include <stdio.h><br /> #define max(a,b) (a>b?a:b)<br /> #define min(a,b) (a>b?b:a)<br /> const int maxn = 1000000; </p> <p>int wa[maxn],wb[maxn],wv[maxn],ws[maxn],a[maxn],sa[maxn],rank[maxn],height[maxn];<br /> int cmp(int *r,int a,int b,int l)<br /> {return r[a]==r[b]&&r[a+l]==r[b+l];}<br /> void da(int *r,int *sa,int n,int m)<br /> {<br /> int i,j,p,*x=wa,*y=wb,*t;<br /> for(i=0;i<m;i++) ws[i]=0;<br /> for(i=0;i<n;i++) ws[x[i]=r[i]]++;<br /> for(i=1;i<m;i++) ws[i]+=ws[i-1];<br /> for(i=n-1;i>=0;i--) sa[--ws[x[i]]]=i;<br /> for(j=1,p=1;p<n;j*=2,m=p)<br /> {<br /> for(p=0,i=n-j;i<n;i++) y[p++]=i;<br /> for(i=0;i<n;i++) if(sa[i]>=j) y[p++]=sa[i]-j;<br /> for(i=0;i<n;i++) wv[i]=x[y[i]];<br /> for(i=0;i<m;i++) ws[i]=0;<br /> for(i=0;i<n;i++) ws[wv[i]]++;<br /> for(i=1;i<m;i++) ws[i]+=ws[i-1];<br /> for(i=n-1;i>=0;i--) sa[--ws[wv[i]]]=y[i];<br /> for(t=x,x=y,y=t,p=1,x[sa[0]]=0,i=1;i<n;i++)<br /> x[sa[i]]=cmp(y,sa[i-1],sa[i],j)?p-1:p++;<br /> }<br /> return;<br /> } </p> <p>void calheight(int *r,int *sa,int n)<br /> {<br /> int i,j,k=0;<br /> for(i=1;i<=n;i++)rank[sa[i]]=i;<br /> for(i=0;i<n;height[rank[i++]]=k)<br /> for(k?k--:0,j=sa[rank[i]-1];r[i+k]==r[j+k];k++);<br /> }</p> <p>int n,k;<br /> bool ask(int len)<br /> {<br /> int i,MAX,MIN,cnt;<br /> MAX = n; MIN = 0;cnt = 1; //初始要为1，不是0<br /> for (i=1;i<=n;i++)<br /> {<br /> if(height[i]<len)<br /> {<br /> MAX = sa[i];<br /> MIN = sa[i];<br /> cnt = 1;<br /> }<br /> else<br /> {<br /> MAX = max(MAX,sa[i]);<br /> MAX = max(MAX,sa[i-1]);<br /> MIN = min(MIN,sa[i]);<br /> MIN = min(MIN,sa[i-1]);<br /> cnt ++;<br /> if(cnt>=k)<br /> return true;<br /> }<br /> }<br /> return false;<br /> }</p> <p>int main()<br /> {<br /> int i,m;<br /> while (~scanf("%d%d",&n,&k))<br /> {<br /> m = 0;<br /> for(i=0;i<n;i++)<br /> {<br /> scanf("%d",&a[i]);<br /> m = max(m,a[i]);<br /> }<br /> a[n] = 0;<br /> da(a,sa,n+1,m+1);<br /> calheight(a,sa,n);<br /> int low,high,mid;<br /> low = 0;<br /> high = n;<br /> while (low<high) //二分枚举<br /> {<br /> mid = (low+high+1)>>1;<br /> if(ask(mid)) low = mid;<br /> else high = mid - 1;<br /> }<br /> printf("%d/n",low);<br /> }<br /> return 0;<br /> }<br />