acdream 1430 SETI 后缀数组+height分组

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这题昨天比赛的时候逗了，后缀想不出来，因为n^2的T了，就没往后缀数组想……而且之后解题的人又说用二分套二分来做，然后就更不会了……

刚才看了题解，唉……原来题解说n^2的也可以过，然后就……这样了！

#pragma comment(linker, "/STACK:1024000000,1024000000")#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>#include<map>#include<queue>#include<set>#include<cmath>#include<bitset>#define mem(a,b) memset(a,b,sizeof(a))#define lson i<<1,l,mid#define rson i<<1|1,mid+1,r#define llson j<<1,l,mid#define rrson j<<1|1,mid+1,r#define INF 0x7fffffff#define seed 13131#define seed1 1313#define maxn 20005typedef long long ll;typedef unsigned long long ull;using namespace std;void radix(int *str,int *a,int *b,int n,int m){    static int count[maxn];    mem(count,0);    for(int i=0; i<n; i++) ++count[str[a[i]]];    for(int i=1; i<=m; i++) count[i]+=count[i-1];    for(int i=n-1; i>=0; i--) b[--count[str[a[i]]]]=a[i];}void suffix(int *str,int *sa,int n,int m) //倍增算法计算出后缀数组sa{    static int rank[maxn],a[maxn],b[maxn];    for(int i=0; i<n; i++) rank[i]=i;    radix(str,rank,sa,n,m);    rank[sa[0]]=0;    for(int i=1; i<n; i++)        rank[sa[i]]=rank[sa[i-1]]+(str[sa[i]]!=str[sa[i-1]]);    for(int i=0; 1<<i<n; i++)    {        for(int j=0; j<n; j++)        {            a[j]=rank[j]+1;            b[j]=j+(1<<i)>=n?0:rank[j+(1<<i)]+1;            sa[j]=j;        }        radix(b,sa,rank,n,n);        radix(a,rank,sa,n,n);        rank[sa[0]]=0;        for(int j=1; j<n; j++)            rank[sa[j]]=rank[sa[j-1]]+(a[sa[j-1]]!=a[sa[j]]||b[sa[j-1]]!=b[sa[j]]);    }}void calcHeight(int *str,int *sa,int *h,int *rank,int n) //求出最长公共前缀数组h{    int k=0;    h[0]=0;    for(int i=0; i<n; i++) rank[sa[i]]=i;    for(int i=0; i<n; i++)    {        k=k==0?0:k-1;        if(rank[i])            while(str[i+k]==str[sa[rank[i]-1]+k]) k++;        else k=0;        h[rank[i]]=k;    }}int a[maxn],sa[maxn],height[maxn],rank[maxn];char s[maxn];int main(){    //freopen("1.txt","r",stdin);    scanf("%s",s);    int n=strlen(s);    copy(s,s+n,a);    suffix(a,sa,n,150);    calcHeight(a,sa,height,rank,n);    int Max,Min,sum=0;    for(int i=1;i<=n/2;i++)    {        Max=Min=sa[0];        for(int j=1;j<=n;j++)        {            if(height[j]<i||j==n)            {                if(Max-Min>=i) sum++;                Max=Min=sa[j];            }            else            {                Max=max(Max,sa[j]);                Min=min(Min,sa[j]);            }        }    }    printf("%d\n",sum);    return 0;}

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