感觉 $push\_down$ 的思路和题解的有些不一样，但是为什么挂了呢？

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 1100000;
int n, q, a[N];
int id, l, r, x;
struct Tree {
	int l, r;
	int num;
	pair<int, int> lz;
} tree[N << 2];
inline void push_up(int u) {
	tree[u].num = max(tree[u << 1].num, tree[u << 1 | 1].num);
}
inline void push_down(int u) {
	if (tree[u].lz.first) {
		if (tree[u].lz.first == 1) {
			tree[u << 1].lz = make_pair(1, tree[u].lz.second);
			tree[u << 1 | 1].lz = make_pair(1, tree[u].lz.second);
		} else {
			tree[u << 1].lz = make_pair(tree[u << 1].lz.first, tree[u << 1].lz.second + tree[u].lz.second);
			tree[u << 1 | 1].lz = make_pair(tree[u << 1 | 1].lz.first, tree[u << 1 | 1].lz.second + tree[u].lz.second);
		}
		if (tree[u << 1].lz.first == 1) {
			tree[u << 1].num = tree[u << 1].lz.second;
		} else {
			tree[u << 1].num += tree[u].lz.second;
		}
		if (tree[u << 1 | 1].lz.first == 1) {
			tree[u << 1 | 1].num = tree[u << 1 | 1].lz.second;
		} else {
			tree[u << 1 | 1].num += tree[u].lz.second;
		}
		tree[u].lz = make_pair(0, 0);
	}
	return ;
}
inline void build(int u, int l, int r) {
	tree[u].l = l, tree[u].r = r;
	if (l == r) {
		tree[u].num = a[l];
		return ;
	}
	int mid = l + r >> 1;
	build(u << 1, l, mid);
	build(u << 1 | 1, mid + 1, r);
	push_up(u);
}
inline void chg(int u, int l, int r, int val) {
	if (l <= tree[u].l && tree[u].r <= r) {
		tree[u].num = val;
		tree[u].lz = make_pair(1, val);
		return ;
	}
	push_down(u);
	if (l <= tree[u << 1].r) chg(u << 1, l, r, val);
	if (r >= tree[u << 1 | 1].l) chg(u << 1 | 1, l, r, val);
	push_up(u);
}
inline void add(int u, int l, int r, int val) {
	if (l <= tree[u].l && tree[u].r <= r) {
//		cout << u << ' ' << tree[u].l << ' ' << tree[u].r << ' ' << "yuan = " << tree[u].num << endl;
		tree[u].num += val;
		tree[u].lz = make_pair(2, val);
		return ;
	}
	push_down(u);
	if (l <= tree[u << 1].r) add(u << 1, l, r, val);
	if (r >= tree[u << 1 | 1].l) add(u << 1 | 1, l, r, val);
	push_up(u);
}
inline int search(int u, int l, int r) {
	if (l <= tree[u].l && tree[u].r <= r) {
		return tree[u].num;
	}
	push_down(u);
	int sum = -1e18;
	if (l <= tree[u << 1].r) sum = max(sum, search(u << 1, l, r));
	if (r >= tree[u << 1 | 1].l) sum = max(sum, search(u << 1 | 1, l, r));
	return sum;
}
signed main() {
	scanf("%lld%lld", &n, &q);
	for (int i = 1; i <= n; i++) {
		scanf("%lld", &a[i]);
	}
	build(1, 1, n);
	for (int i = 1; i <= q; i++) {
		scanf("%lld", &id);
		if (id == 1) {
			scanf("%lld%lld%lld", &l, &r, &x);
			chg(1, l, r, x);
		} else if (id == 2) {
			scanf("%lld%lld%lld", &l, &r, &x);
			add(1, l, r, x);
		} else {
			scanf("%lld%lld", &l, &r);
			printf("%lld\n", search(1, l, r));
		}
	}
	return 0;
}