[poj][3261][Milk Patterns]

#include <cstdio>
#include <cstring>
#include <map>

using namespace std;

const int N = 1000000+10;
int ua
, ub
, us
, n, m, arr
, sa
, t, cnt;
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 n,int m){
int i,j,p,*x=ua,*y=ub,*t;
for (i=0;i<m;i++) us[i]=0;
for (i=0;i<n;i++) us[x[i]=r[i]]++;
for (i=1;i<m;i++) us[i]+=us[i-1];
for (i=n-1;i>=0;i--) sa[--us[x[i]]]=i;
for (j=1,p=1;p<n;j*=2,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++) us[i]=0;
for (i=0;i<n;i++) us[x[i]]++;
for (i=1;i<m;i++) us[i]+=us[i-1];
for (i=n-1;i>=0;i--) sa[--us[x[y[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++;
}
}
int rank
,height
;
void calheight(int *r,int n){
int i,j,k=0;
for (i=1;i<=n;i++)rank[sa[i]]=i;
for (i=0;i<n;height[rank[i++]]=k)
for (k?k--:0,j=sa[rank[i]-1];r[i+k]==r[j+k];k++);
}
void solve(int k){
int i, tot, maxx=0;
int low=1, high=n, mid;
while (low <= high){
mid = low + (high - low) / 2;
for (tot=1, i=2; i<=n; i++){
if (height[i]>=mid)tot++;
else tot = 1;
if (tot >= k) break;
}
if (tot >= k)low=mid+1,maxx=mid;
else high=mid-1;
}
printf("%d\n", maxx);
}

int main(){
//freopen("D:/a.txt", "r", stdin);
while (~scanf("%d%d", &n, &m)){
memset(arr, 0, sizeof(arr));
map<int,int>ma;
cnt = 1;
for (int i=0; i<n; i++){
scanf("%d", &t);
if (ma.find(t)==ma.end())ma[t]=cnt++;
arr[i] = ma[t];
}
arr
= 0;
da(arr, n+1, cnt); //算后缀数组的时候要把最后一个算在内，排名才是从1开始的，因为空串排在第0个。
calheight(arr, n);
solve(m);
}
return 0;
}