bzoj3879

题解：

SA是唯一听懂了怎么求的东西

显然对每个询问只把询问到的那些位置拉出来用单调栈维护就行了

代码：

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
typedef long long ll;
const int N=500005;
char s[N];
int sa[N],rank[N],height[N],cnt[N],f[N],a[N*6],sta[N],mn[N][25],log[N],num[N],n,q,m=26;
int get(int l,int r)
{
    int k=log[r-l+1];
    return min(mn[l][k],mn[r-(1<<k)+1][k]);
}
int main()
{
    ll now,ans;
    int x,p,top,tot;
    scanf("%d%d",&n,&q);
    scanf("%s",s+1);
    for (int i=1;i<=n;i++)cnt[rank[i]=f[i]=s[i]-'a'+1]++;
    for (int i=1;i<=m;i++)cnt[i]+=cnt[i-1];
    for (int i=n;i;i--)sa[cnt[f[i]]--]=i;
    for (int k=1;k<=n;k<<=1)
     {
         p=0;
         for (int i=n-k+1;i<=n;i++)f[++p]=i;
         for (int i=1;i<=n;i++)
          if (sa[i]>k)f[++p]=sa[i]-k;
         for (int i=1;i<=m;i++)cnt[i]=0;
        for (int i=1;i<=n;i++)cnt[rank[f[i]]]++;
        for (int i=1;i<=m;i++)cnt[i]+=cnt[i-1];
        for (int i=n;i;i--)sa[cnt[rank[f[i]]]--]=f[i];
        for (int i=1;i<=n;i++)f[i]=rank[i];
        rank[sa[1]]=1;
        for (int i=2;i<=n;i++)
         if (f[sa[i]]!=f[sa[i-1]]||f[sa[i]+k]!=f[sa[i-1]+k])
          rank[sa[i]]=rank[sa[i-1]]+1;
         else rank[sa[i]]=rank[sa[i-1]];
        m=rank[sa[n]];
        if (m>=n)break; 
     }
    for (int i=1;i<=n;i++)
     {
         height[rank[i]]=height[rank[i-1]];
         if (height[rank[i]])height[rank[i]]--;
         while (s[i+height[rank[i]]]==s[sa[rank[i]-1]+height[rank[i]]])
          height[rank[i]]++;
     } 
    for (int i=1;i<=n;i++)mn[i][0]=height[i];
    for (int k=1;(1<<k)<=n;k++)log[1<<k]=k;
    for (int i=3;i<=n;i++)
     if (!log[i])log[i]=log[i-1];
    for (int k=1;(1<<k)<=n;k++)
     for (int i=1;i+(1<<k)-1<=n;i++)
      mn[i][k]=min(mn[i][k-1],mn[i+(1<<k-1)][k-1]);
    while (q--)
     {
         scanf("%d",&m);
         for (int i=1;i<=m;i++)
          {
              scanf("%d",&x);
              a[i]=rank[x];
         }
        sort(a+1,a+m+1);
        m=unique(a+1,a+m+1)-a-1;
        now=sta[top=1]=n-sa[a[1]]+1;
        ans=0;
        num[1]=1;
        for (int i=2;i<=m;i++)
         {
             x=get(a[i-1]+1,a[i]);
             tot=0;
             while (top&&x<=sta[top])
              {
                  now-=(ll)num[top]*sta[top];
                  tot+=num[top];
                  top--;
             }
            now+=(ll)x*tot;
            ans+=now;
            sta[++top]=x;
            num[top]=tot;
            sta[++top]=n-sa[a[i]]+1;
            num[top]=1;
            now+=sta[top];
         } 
        printf("%lld
",ans); 
     }   
}