线段树

重点
1. build，modify，query，pushup，pushdown五种操作
2. 建树的时候，区间大小是确定的，只需要记住区间长度即可

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 200010;
int n, m, p;
struct node {
    int l, r;
    int v;
} tr[N << 2];

void build(int u, int l, int r) {
    tr[u] = {l, r};
    if (l == r) return ;
    int mid = l + r >> 1;
    build(u << 1, l, mid), build(u << 1 | 1, mid + 1, r);
}

int query(int u, int l, int r) {  // 从u结点开始向下找，在区间l，r中的最大值
    if (tr[u].l >= l && tr[u].r <= r) return tr[u].v;
    int mid = tr[u].l + tr[u].r >> 1;
    int v = 0;
    if (l <= mid) v = query(u << 1, l, r);
    if (r > mid) v = max(v, query(u << 1 | 1, l, r));
    return v;
}

void pushup(int u) {
    tr[u].v = max(tr[u << 1].v, tr[u << 1 | 1].v);
}

void modify(int u, int x, int v) {  //从u节点开始向下找序号为x的叶子结点
    if (tr[u].l == x && tr[u].r == x) tr[u].v = v;
    else {
        int mid = tr[u].l + tr[u].r >> 1;
        if (x <= mid) modify(u << 1, x, v);
        else modify(u << 1 | 1, x, v);
        pushup(u);
    }
}

int main() {
    cin >> m >> p;
    build(1, 1, m);

    char s[2];
    int l, t, last;
    while (m--) {
        scanf("%s", s);
        if (*s == 'Q') {
            scanf("%d", &l);
            last = query(1, n - l + 1, n);
            printf("%d\n", last);
        } else {
            scanf("%d", &t);
            modify(1, n + 1, (t + last) % p);
            n++;
        }
    }


    return 0;
}