思路

改一下线段树的模板就行了。每次添加数的时候len+1，查询区间是[len-L+1,len]。

代码

#include <bits/stdc++.h>
#define int long long
using namespace std;
typedef long long ll;
const int maxn = 2e5 + 7;

char ch;
int x, m, mod, a = 0, tr[maxn << 2];

void add(int p, int l, int r, int pos, int x) {
    if (l == r) {
        tr[p] = (x + a + mod) % mod;
        return;
    }

    int mid = l + r >> 1;

    if (pos <= mid)
        add(p << 1, l, mid, pos, x);
    else
        add(p << 1 | 1, mid + 1, r, pos, x);

    tr[p] = max(tr[p << 1], tr[p << 1 | 1]);
}

int query(int p, int l, int r, int ql, int qr) {
    if (ql <= l && r <= qr)
        return tr[p];

    int mid = l + r >> 1, res = 0;

    if (ql <= mid)
        res = max(res, query(p << 1, l, mid, ql, qr));

    if (qr > mid)
        res = max(res, query(p << 1 | 1, mid + 1, r, ql, qr));

    return res;
}

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> m >> mod;
    memset(tr, 0, sizeof(tr));
    int len = 0;

    for (int i = 1; i <= m; i++) {
        cin >> ch >> x;

        if (ch == 'A') {
            add(1, 1, m, len + 1, x);
            len++;
        }

        if (ch == 'Q') {
            a = query(1, 1, m, len - x + 1, len);
            cout << a << endl;
        }

        //  for(int i=1;i<=4*len;i++) cout<<tr[i]<<" ";
    }

    return 0;
}