我的思路

#include <iostream>
#define lowbit(x) ((x)&(-(x)))
#define DEBUG 1
#if DEBUG
const int N = 6;
#else
const int N = 1e5 + 10;
#endif
typedef long long lint;

int n, m;
lint a[N], d[N], f[N];
// d[i] = a[i] - a[i - 1], f[i] = i * d[i]

lint sum(int p, lint *t) { // 查询 t 中 [1,p] 之和
	lint res = 0;
	for (int i = p; i; i -= lowbit(i))
		res += t[i];
	return res;
}

lint ask(int p) {
	lint sum1 = sum(p, d);
	lint sum2 = sum(p, f);
	return sum1 * (p + 1) - sum2;
//	return sum(p, d) * (p + 1) - sum(p, f);
}

lint query(int l, int r) {
	return ask(r) - ask(l - 1);
}

void add(int p, lint x, lint *t) {
	for (int i = p; i <= n; i += lowbit(i)) t[i] += x;
}

void update(int l, int r, lint x) {
	add(l, x, d), add(r + 1, -x, d);
	add(l, x * l, f);
	add(r + 1, -x * r, f);
}

int main() {
//	std::cin.tie(0)->sync_with_stdio(0);
	std::cin >> n >> m;
	for (int i = 1; i <= n; ++i) std::cin >> a[i];
	for (int i = 1; i <= n; ++i) add(i, a[i] - a[i - 1], d);
	for (int i = 1; i <= n; ++i) add(i, i * (a[i] - a[i - 1]), f);
	for (int op, x, y, k; m; --m) {
		std::cin >> op >> x >> y;
		if (op == 1) std::cin >> k, update(x, y, k);
		else std::cout << query(x, y) << '\n';
	}
	std::cout.flush();
	return 0;
}