@[Annie07](/user/556457) 开那么大，那么多的数组，不MLE才怪
by shengyeqi @ 2023-08-09 15:13:32
我改成了三个数组，也会超内存，怎么办
```cpp
#include<bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
int n, m;
double sum[N * 4], sqr[N * 4];
void build (int k, int l, int r) {
if (l == r) {
scanf("%lf", &sum[k]);
sqr[k] = sum[k] * sum[k];
return;
}
int mid = (l + r) >> 1;
build(k * 2, l, mid);
build(k * 2 + 1, mid + 1, r);
sum[k] = sum[k * 2] + sum[k * 2 + 1];
sqr[k] = sqr[k * 2] + sqr[k * 2 + 1];
}
double tag[N * 4];
void pushdown(int k, int l, int r);
double ask1(int k, int l, int r, int x, int y) {
if (r < x || y < l) return 0;
if (x <= l && r <= y) return sum[k];
pushdown(k, l, r);
int mid = (l + r) >> 1;
return ask1(k * 2, l, mid, x, y) + ask1(k * 2 + 1, mid + 1, r, x, y);
}
double ask2(int k, int l, int r, int x, int y) {
if (r < x || y < l) return 0;
if (x <= l && r <= y) {
return sqr[k];
}
pushdown(k, l, r);
int mid = (l + r) >> 1;
return ask2(k * 2, l, mid, x, y) + ask2(k * 2 + 1, mid + 1, r, x, y);
}
void pushdown(int k, int l, int r) {
int mid = (l + r) >> 1;
if (tag[k]) {
sqr[k * 2] += 2 * tag[k] * ask1(1, 1, n, l, mid) + tag[k] * tag[k] * (mid - l + 1);
sqr[k * 2 + 1] += 2 * tag[k] * ask1(1, 1, n, mid + 1, r) + tag[k] * tag[k] * (r - mid);
sum[k * 2] += tag[k] * (mid - l + 1);
sum[k * 2 + 1] += tag[k] * (r - mid);
tag[k * 2] += tag[k],
tag[k * 2 + 1] += tag[k];
tag[k] = 0;
}
}
void update(int k, int l, int r, int x, int y, double v) {
if (r < x || y < l) return;
if (x <= l && r <= y) {
sqr[k] += 2 * v * ask1(1, 1, n, l, r) + v * v * (r - l + 1);
sum[k] += v * (r - l + 1);
tag[k] += v;
return;
}
pushdown(k, l, r);
int mid = (l + r) >> 1;
update(k * 2, l, mid, x, y, v);
update(k * 2 + 1, mid + 1, r, x, y, v);
sqr[k] = sqr[k * 2] + sqr[k * 2 + 1];
sum[k] = sum[k * 2] + sum[k * 2 + 1];
}
int main() {
scanf("%d%d", &n, &m);
build(1, 1, n);
int op, x, y;
double k, s, tmp;
for (int i = 1; i <= m; i++) {
scanf("%d", &op);
if (op == 1) {
scanf("%d%d%lf", &x, &y, &k);
update(1, 1, n, x, y, k);
} else if (op == 2) {
scanf("%d%d", &x, &y);
printf("%.4lf\n", ask1(1, 1, n, x, y) / (y - x + 1));
} else if (op == 3) {
scanf("%d%d", &x, &y);
s = ask1(1, 1, n, x, y);
tmp = ask2(1, 1, n, x, y) - s * (s / (y - x + 1));
printf("%.4f\n", tmp / (y - x + 1));
}
}
return 0;
}
```
by Annie07 @ 2023-08-09 15:31:25