POJ 3261Milk Patterns可重叠至少出现K次最长子串 二分+height分段

#include <iostream>#include <algorithm>#include <cstdio>#include <cstring>#include <cmath>#include <queue>#define INF 0x3f3f3f3fusing namespace std;#define F(x) ((x) / 3 + ((x) % 3 == 1 ? 0 : tb))#define G(x) ((x) < tb ? (x) * 3 + 1 :((x) - tb) * 3 + 2)const int MAXN = 70001;int wa[MAXN],wb[MAXN],ws[MAXN],wv[MAXN],wsd[MAXN],r[MAXN],sa[MAXN];int c0(int *r,int a,int b){return r[a] == r[b] && r[a + 1] == r[b + 1] && r[a + 2] == r[b + 2];}int c12(int k,int *r,int a,int b){if(k == 2) return r[a] < r[b] || r[a] == r[b] && c12(1,r,a + 1,b + 1);else return r[a] < r[b] || r[a] == r[b] && wv[a + 1]< wv[b + 1];}void sort(int *r,int *a,int *b,int n,int m){    int i;    for(i = 0 ; i < n ; i++) wv[i] = r[a[i]];    for(i = 0 ; i < m ; i++) wsd[i] = 0;    for(i = 0 ; i < n ; i++) wsd[wv[i]]++;    for(i = 1 ; i < m ; i++) wsd[i] += wsd[i - 1];    for(i = n - 1 ; i >= 0 ; i--) b[--wsd[wv[i]]] = a[i];}void dc3(int *r,int *sa,int n,int m){    int i,j,*rn = r + n ,*san = sa + n,ta = 0,tb = (n + 1) / 3,tbc = 0,p;    r[n] = r[n + 1] = 0;    for(i = 0 ; i < n ; i++) if(i % 3 != 0) wa[tbc++] = i;    sort(r + 2,wa,wb,tbc,m);    sort(r + 1,wb,wa,tbc,m);    sort(r,wa,wb,tbc,m);    for(p = 1,rn[F(wb[0])] = 0,i = 1 ; i < tbc ; i++)        rn[F(wb[i])] = c0(r,wb[i - 1],wb[i])?p - 1 : p++;    if(p < tbc) dc3(rn,san,tbc,p);    else for(i = 0 ; i < tbc ; i++) san[rn[i]] = i;    for(i = 0 ;i < tbc ; i++) if(san[i] < tb) wb[ta++] = san[i] * 3;    if(n % 3 == 1) wb[ta++] = n - 1;    sort(r,wb,wa,ta,m);    for(i = 0 ; i < tbc ; i++) wv[wb[i] = G(san[i])] = i;    for(i = 0,j = 0,p = 0 ; i < ta && j < tbc ; p++)        sa[p]=c12(wb[j] % 3,r,wa[i],wb[j]) ? wa[i++] : wb[j++];    for(;i < ta ; p++) sa[p] = wa[i++];    for(;j < tbc ; p++) sa[p] = wb[j++];}int Rank[MAXN],height[MAXN];void calheight(int *r,int *sa,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++);}int a[MAXN];int b[MAXN];bool judge(int mid,int n,int k){    int cas = 2;    while(true){        while(cas<=n && height[cas] < mid) cas++;        if(cas > n) return false;        int cnt = 1;        while(cas<=n && height[cas] >= mid){            cnt++;            cas++;        }        if(cnt >= k) return true;    }    return false;}int main(){    int n,k;    while(~scanf("%d%d",&n,&k)){        for(int i = 0; i < n; ++i){            scanf("%d",&a[i]);            b[i] = a[i];        }        sort(b,b+n);        int siz = unique(b,b+n)-b;        for(int i = 0; i < n; ++i){            a[i] = lower_bound(b,b+n,a[i])-b+1;        }        a[n] = 0;        dc3(a,sa,n+1,20001);        calheight(a,sa,n);        int l = 2,r = n;        int ans = 0;        while(l <= r){            int mid = (l+r)>>1;            if(judge(mid,n,k)){                ans = mid;                l = mid+1;            }            else{                r = mid-1;            }        }        printf("%d\n",ans);    }    return 0;}