这个就是线段树模板

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int mod;
const int N=200000+5;
struct node{
    int l,r;
    int v=0;
    int id;
}tree[N<<4];
int a[N];
void build(int flag,int l,int r)
{
    if(l==r){
        tree[flag].l=tree[flag].r=l;
        return ;
    }
    int mid=(l+r)/2;
    tree[flag].l=l;
    tree[flag].r=r;
    build(flag*2,l,mid);
    build(flag*2+1,mid+1,r);
}

int ask(int flag,int l,int r)
{
    if(tree[flag].l>=l&&tree[flag].r<=r){
        //cout<<"ask="<<tree[flag].v;
        return tree[flag].v;
    }
    int left=-999999,right=-999999;
    if(l<=tree[flag*2].r){
        left=ask(flag*2,l,r);
    }
    if(r>=tree[flag*2+1].l){
        right=ask(flag*2+1,l,r);
    }
    tree[flag].v=max(max(left,right),tree[flag].v);
    return max(left,right);
}

int add(int flag,int dig,int num)
{
    if(tree[flag].l==tree[flag].r){
        tree[flag].v=num;
        return num;
    }
    int l=-999999;
    if(dig<=tree[flag*2].r){
        l=add(flag*2,dig,num);
    }
    else
        l=add(flag*2+1,dig,num);

    tree[flag].v=max(l,tree[flag].v);
}

int main()
{
    int m;
    scanf("%d",&m);
    scanf("%d",&mod);
    build(1,1,N-5);
    ll last=0;
    int n=0;
    while(m--)
    {
        char ch;
        cin>>ch;
        int num;
        scanf("%d",&num);
        if(ch=='A'){
            n++;
            add(1,n,(last+num)%mod);
            //cout<<tree[1].v<<"sdfsd"<<endl;
        }else{
            last=ask(1,n-num+1,n);
            printf("%d\n",last);
            //cout<<tree[1].v<<"sdfsd"<<endl;
        }
    }
    return 0;
}