后缀自动机

http://hihocoder.com/problemset/problem/1449

求长度为k的子串出现次数最多的是多少

求完sam后,直接topo,然后更新所有长度即可

//#pragma comment(linker, "/stack:200000000")
//#pragma GCC optimize("Ofast,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define pi acos(-1.0)
#define ll long long
#define mod (1000000007)
#define C 0.5772156649
#define ls l,m,rt<<1
#define rs m+1,r,rt<<1|1
#define pil pair<int,ll>
#define pii pair<int,int>
#define ull unsigned long long
#define base 1000000000000000000
#define fio ios::sync_with_stdio(false);cin.tie(0)

using namespace std;

const double g=10.0,eps=1e-12;
const int N=2000000+10,maxn=1200000+10,inf=0x3f3f3f3f,INF=0x3f3f3f3f3f3f3f3f;

char s[N],p[N];
int sz[N],c[N],a[N],ans[N];
struct SAM{
    int last,cnt;
    int ch[N<<1][26],fa[N<<1],l[N<<1];
    void ins(int c){
        int p=last,np=++cnt;last=np;l[np]=l[p]+1;
        for(;p&&!ch[p][c];p=fa[p])ch[p][c]=np;
        if(!p)fa[np]=1;
        else{
            int q=ch[p][c];
            if(l[p]+1==l[q])fa[np]=q;
            else{
                int nq=++cnt;l[nq]=l[p]+1;
                memcpy(ch[nq],ch[q],sizeof(ch[q]));
                fa[nq]=fa[q];fa[q]=fa[np]=nq;
                for(;ch[p][c]==q;p=fa[p])ch[p][c]=nq;
            }
        }
        sz[np]=1;
    }
    void build(){
        scanf("%s",s+1);
        int len=strlen(s+1);
        last=cnt=1;
        for(int i=1;i<=len;i++)ins(s[i]-'a');
        topo();
    }
    void topo(){
        for(int i=1;i<=cnt;i++)c[l[i]]++;
        for(int i=1;i<=cnt;i++)c[i]+=c[i-1];
        for(int i=1;i<=cnt;i++)a[c[l[i]]--]=i;
    }
    void cal()
    {
        for(int i=cnt;i;i--)
        {
            int p=a[i];
            sz[fa[p]]+=sz[p];
            ans[l[p]]=max(ans[l[p]],sz[p]);
        }
        int len=strlen(s+1);
        for(int i=1;i<=len;i++)
            printf("%d
",ans[i]);
    }
}sam;
int main()
{
    sam.build();
    sam.cal();
    return 0;
}

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