ICPC网络赛 L DP

#include<bits/stdc++.h>
#define M 2000005
#define L long long
#define MOD 998244353
using namespace std;

L I[M],IC[M],ICP[M],ICPC[M];
L C[M],CP[M],CPC[M];
L P[M],PC[M];

L c(int l,int r){return (C[r]-C[l-1]+MOD)%MOD;}
L pc(int l,int r){
    L sumpc=(PC[r]-PC[l-1]+MOD)%MOD;
    L p_c=P[l-1]*c(l,r)%MOD;
    return (sumpc-p_c+MOD)%MOD;
}

L cpc(int l,int r){
    L sumcpc=(CPC[r]-CPC[l-1]+MOD)%MOD;
    L c_pc=C[l-1]*pc(l,r)%MOD;
    L cp_c=CP[l-1]*c(l,r)%MOD;
    return (sumcpc-c_pc-cp_c+MOD+MOD)%MOD;
}

L icpc(int l,int r){
    L sumicpc=(ICPC[r]-ICPC[l-1]+MOD)%MOD;
    L i_cpc=I[l-1]*cpc(l,r)%MOD;
    L ic_pc=IC[l-1]*pc(l,r)%MOD;
    L icp_c=ICP[l-1]*c(l,r)%MOD;
    return (sumicpc-i_cpc-ic_pc-icp_c+MOD*3LL)%MOD;
}

int n,q;
L ans=0;
char ch[M];

L x,a,b,p;

L get(){
    x=(a*x+b)%p;
    return x%n+1;
}

L u[M],v[M];

int main(){
    cin>>n>>q;
    scanf("%s",ch+1);
    for(int i=1;i<=n;i++){
        I[i]=I[i-1]+(ch[i]=='I');
        C[i]=C[i-1]+(ch[i]=='C');
        P[i]=P[i-1]+(ch[i]=='P');
        
        IC[i]=(IC[i-1]+I[i-1]*(ch[i]=='C'))%MOD;
        CP[i]=(CP[i-1]+C[i-1]*(ch[i]=='P'))%MOD;
        PC[i]=(PC[i-1]+P[i-1]*(ch[i]=='C'))%MOD;
        
        ICP[i]=(ICP[i-1]+IC[i-1]*(ch[i]=='P'))%MOD;
        CPC[i]=(CPC[i-1]+CP[i-1]*(ch[i]=='C'))%MOD;
        
        ICPC[i]=(ICPC[i-1]+ICP[i-1]*(ch[i]=='C'))%MOD;
    }
    cin>>x>>a>>b>>p;
    for(int i=1;i<=q;i++) u[i]=get();
    for(int i=1;i<=q;i++) v[i]=get();
    for(int i=1;i<=q;i++){
        int l=u[i],r=v[i];
        //int l=get(),r=get();
        if(l>r) swap(l,r);
        L out=icpc(l,r);
        ans=(out+ans)%MOD;
    }
    cout<<ans<<endl;
}