标记永久化线段树 区间更新求和

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
typedef long long ll;
const int MAXN = 100009;
int n, q;
ll sum[MAXN * 4], add[MAXN * 4];
void build(int l, int r, int rt)
{
    add[rt] = 0;
    if (l == r) {
        scanf("%lld", &sum[rt]);
        return;
    }
    int mid = (l + r) >> 1;
    build(l, mid, rt << 1);
    build(mid + 1, r, rt << 1 | 1);
    sum[rt] = (sum[rt << 1] + sum[rt << 1 | 1]);
}
void update(int l, int r, int rt, int ql, int qr, int c)
{
    sum[rt] += c * (qr - ql + 1);
    if (l == ql && r == qr) {
        add[rt] += c;
        return;
    }
    int mid = (l + r) >> 1;
    if (qr <= mid) update(l, mid, rt << 1, ql, qr, c);
    else if (ql > mid) update(mid + 1, r, rt << 1 | 1, ql, qr, c);
    else {
        update(l, mid, rt << 1, ql, mid, c);
        update(mid + 1, r, rt << 1 | 1, mid + 1, qr, c);
    }
}
ll query(int l, int r, int rt, int ql, int qr, ll c)
{
    if (l == ql && r == qr) return sum[rt] + c * (r - l + 1);
    int mid = (l + r) >> 1;
    if (qr <= mid) return query(l, mid, rt << 1, ql, qr, c + add[rt]);
    else if (ql > mid) return query(mid + 1, r, rt << 1 | 1, ql, qr, c + add[rt]);
    else return query(l, mid, rt << 1, ql, mid, c + add[rt]) + query(mid + 1, r, rt << 1 | 1, mid + 1, qr, c + add[rt]);
}
int main()
{
    scanf("%d %d", &n, &q);
    build(1, n, 1);
    char ch[2];
    int x, y, z;
    while (q--) {
        scanf("%s", ch);
        if (ch[0] == 'Q') {
            scanf("%d %d", &x, &y);
            printf("%lld\n", query(1, n, 1, x, y, 0));
        } else {
            scanf("%d %d %d", &x, &y, &z);
            update(1, n, 1, x, y, z);
        }
    }
    return 0;
}