bzoj5055 膜法师

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 using namespace std;
 6 typedef long long ll;
 7 int Mod=19260817;
 8 int n,sz;
 9 ll ans,sum1[300001],sum2[300001],has[300001],a[300001],b[300001];
10 ll c[1200001][3];
11 void pushup(int rt,int p)
12 {
13     c[rt][p]=(c[rt*2][p]+c[rt*2+1][p])%Mod;
14 }
15 void update(int rt,int l,int r,int x,ll d,int p)
16 {
17     if (l==r)
18     {
19         c[rt][p]+=d;
20         c[rt][p]%=Mod;
21         return;
22     }
23     int mid=(l+r)/2;
24     if (x<=mid) update(rt*2,l,mid,x,d,p);
25     else update(rt*2+1,mid+1,r,x,d,p);
26     pushup(rt,p);
27 }
28 ll query(int rt,int l,int r,int L,int R,int p)
29 {
30     if (l>=L&&r<=R)
31     {
32         return c[rt][p];
33     }
34     int mid=(l+r)/2;
35     ll s=0;
36     if (L<=mid) s+=query(rt*2,l,mid,L,R,p);
37     s%=Mod;
38     if (R>mid) s+=query(rt*2+1,mid+1,r,L,R,p);
39     s%=Mod;
40     return s;
41 }
42 int main()
43 {
44     int i;
45     cin>>n;
46     for (i=1; i<=n; i++)
47     {
48         scanf("%lld",&a[i]);
49         b[i]=a[i];
50     }
51     sort(b+1,b+n+1);
52     sz=unique(b+1,b+n+1)-(b+1);
53     for (i=1; i<=n; i++)
54     {
55         ll x=a[i];
56         a[i]=lower_bound(b+1,b+sz+1,a[i])-b;
57         has[a[i]]=x%Mod;
58     }
59     for (i=1; i<=n; i++)
60     {
61         if (a[i]-1>=1)
62             sum1[i]=query(1,1,sz,1,a[i]-1,1)%Mod;
63         update(1,1,sz,a[i],has[a[i]],1);
64     }
65     for (i=n; i>=1; i--)
66     {
67         if (a[i]+1<=sz)
68             sum2[i]=query(1,1,sz,a[i]+1,sz,2)%Mod;
69         update(1,1,sz,a[i],has[a[i]],2);
70     }
71     for (i=2; i<n; i++)
72     {
73         ans+=(has[a[i]]*sum1[i]%Mod)*sum2[i]%Mod;
74         ans%=Mod;
75     }
76     cout<<ans;
77 }