rt，P1253扶苏的问题，线段树写炸了，只有10pts

大佬们帮帮蒟蒻吧qwq

#include <cstdio>
#include <cstring>
#include <algorithm>
#define ll long long
using namespace std;

const ll inf = 1e18;
const int maxn = 1e6 + 10;
struct node {
	int l, r;
	ll val, tag1, tag2;
} tree[maxn << 2];
int n, q, op, l, r, x, a[maxn];
void push_up(int u) {
	tree[u].val = max(tree[u << 1].val, tree[u << 1 | 1].val);
	return ;
}
void addtag(int u, ll x) {
	if (tree[u].tag2 == inf) {
		tree[u].tag1 += x;
		tree[u].val += x;
	} else {
		tree[u].tag2 += x;
		tree[u].val = tree[u].tag2;
	}
	return ;
}
void tag(int u, ll x) {
	if (tree[u].tag2 == inf) return ;
	tree[u].tag2 = x;
	tree[u].val = x;
	tree[u].tag1 = 0;
	return ;
}
void build(int u, int l, int r) {
	tree[u].l = l;
	tree[u].r = r;
	tree[u].tag2 = inf;
	if (l == r) {
		tree[u].val = a[l];
		return ;
	}
	int mid = l + r >> 1;
	build(u << 1, l, mid);
	build(u << 1 | 1, mid + 1, r);
	push_up(u);
	return ;
}
void push_down(int u) {
	if (tree[u].tag2 == inf) {
		addtag(u << 1, tree[u].tag1);
		addtag(u << 1 | 1, tree[u].tag1);
		tree[u].tag1 = 0;
		return ;
	}
	tag(u << 1, tree[u].tag2);
	tag(u << 1 | 1, tree[u].tag2);
	tree[u].tag2 = inf;
	return ;
}
void add(int u, int l, int r, ll x) {
	if (tree[u].r < l || tree[u].l > r) return ;
	if (l <= tree[u].l && tree[u].r <= r) {
		addtag(u, x);
		return ;
	}
	push_down(u);
	int mid = tree[u].l + tree[u].r >> 1;
	add(u << 1, l, mid, x);
	add(u << 1 | 1, mid + 1, r, x);
	push_up(u);
	return ;
}
void set(int u, int l, int r, ll x) {
	if (tree[u].r < l || tree[u].l > r) return ;
	if (l <= tree[u].l && tree[u].r <= r) {
		tag(u, x);
		return ;
	}
	push_down(u);
	int mid = tree[u].l + tree[u].r >> 1;
	add(u << 1, l, mid, x);
	add(u << 1 | 1, mid + 1, r, x);
	push_up(u);
	return ;
}
ll query(int u, int x, int y) {
	if (tree[u].r < l || tree[u].l > r) return -1e18;
	if (x <= tree[u].l && tree[u].r <= y) return tree[u].val;
	ll res = 0;
	int mid = tree[u].l + tree[u].r >> 1;
	push_down(u);
	res = max(res, query(u << 1, x, y));
	res = max(res, query(u << 1 | 1, x, y));
	return res;
}
int main() {
	scanf("%d %d", &n, &q);
	for (int i = 1; i <= n; i++) scanf("%d", a + i);
	build(1, 1, n);
	while (q--) {
		scanf("%d", &op);
		if (op == 1) {
			scanf("%d %d %d", &l, &r, &x);
			add(1, l, r, x);
		} else if (op == 2) {
			scanf("%d %d %d", &l, &r, &x);
			set(1, l, r, x);
		} else {
			scanf("%d %d", &l, &r);
			printf("%d\n", query(1, l, r));
		}
	}
	return 0;
}