ICPC網絡賽 L DP

 1 #include<bits/stdc++.h>
 2 #define M 2000005
 3 #define L long long
 4 #define MOD 998244353
 5 using namespace std;
 6 
 7 L I[M],IC[M],ICP[M],ICPC[M];
 8 L C[M],CP[M],CPC[M];
 9 L P[M],PC[M];
10 
11 L c(int l,int r){return (C[r]-C[l-1]+MOD)%MOD;}
12 L pc(int l,int r){
13     L sumpc=(PC[r]-PC[l-1]+MOD)%MOD;
14     L p_c=P[l-1]*c(l,r)%MOD;
15     return (sumpc-p_c+MOD)%MOD;
16 }
17 
18 L cpc(int l,int r){
19     L sumcpc=(CPC[r]-CPC[l-1]+MOD)%MOD;
20     L c_pc=C[l-1]*pc(l,r)%MOD;
21     L cp_c=CP[l-1]*c(l,r)%MOD;
22     return (sumcpc-c_pc-cp_c+MOD+MOD)%MOD;
23 }
24 
25 L icpc(int l,int r){
26     L sumicpc=(ICPC[r]-ICPC[l-1]+MOD)%MOD;
27     L i_cpc=I[l-1]*cpc(l,r)%MOD;
28     L ic_pc=IC[l-1]*pc(l,r)%MOD;
29     L icp_c=ICP[l-1]*c(l,r)%MOD;
30     return (sumicpc-i_cpc-ic_pc-icp_c+MOD*3LL)%MOD;
31 }
32 
33 int n,q;
34 L ans=0;
35 char ch[M];
36 
37 L x,a,b,p;
38 
39 L get(){
40     x=(a*x+b)%p;
41     return x%n+1;
42 }
43 
44 L u[M],v[M];
45 
46 int main(){
47     cin>>n>>q;
48     scanf("%s",ch+1);
49     for(int i=1;i<=n;i++){
50         I[i]=I[i-1]+(ch[i]=='I');
51         C[i]=C[i-1]+(ch[i]=='C');
52         P[i]=P[i-1]+(ch[i]=='P');
53         
54         IC[i]=(IC[i-1]+I[i-1]*(ch[i]=='C'))%MOD;
55         CP[i]=(CP[i-1]+C[i-1]*(ch[i]=='P'))%MOD;
56         PC[i]=(PC[i-1]+P[i-1]*(ch[i]=='C'))%MOD;
57         
58         ICP[i]=(ICP[i-1]+IC[i-1]*(ch[i]=='P'))%MOD;
59         CPC[i]=(CPC[i-1]+CP[i-1]*(ch[i]=='C'))%MOD;
60         
61         ICPC[i]=(ICPC[i-1]+ICP[i-1]*(ch[i]=='C'))%MOD;
62     }
63     cin>>x>>a>>b>>p;
64     for(int i=1;i<=q;i++) u[i]=get();
65     for(int i=1;i<=q;i++) v[i]=get();
66     for(int i=1;i<=q;i++){
67         int l=u[i],r=v[i];
68         //int l=get(),r=get();
69         if(l>r) swap(l,r);
70         L out=icpc(l,r);
71         ans=(out+ans)%MOD;
72     }
73     cout<<ans<<endl;
74 }