RE and MLE

#include <bits/stdc++.h>

using namespace std;
#define int long long
#define root 1, 1, n
#define lson fa << 1, l, mid
#define rson fa << 1 | 1, mid + 1, r

const int N = 1e5 + 10;

int n, m;

struct node{
	int maxn, suf, pre, sum;
	node(){
		maxn = suf = pre = sum = -1e9;
	}
	void init(int x){
		maxn = sum = pre = suf = x;
	}
}tree[N << 2];
int a[N];

node operator + (const node &l, const node &r){
	node res;
	res.sum = l.sum + r.sum;
	res.maxn = max(l.maxn, max(r.maxn, l.suf + r.pre));
	res.pre = max(l.pre, l.sum + r.pre);
	res.suf = max(r.suf, r.sum + l.suf);
	return res;
}

inline void push_up(int fa){
	tree[fa] = tree[fa << 1] + tree[fa << 1 | 1];
}

inline void build(int fa, int l, int r){
	if (l == r){
		tree[fa].init(a[l]);
		return;
	}
	int mid = l + r >> 1;
	build(lson);
	build(rson);
	push_up(fa);
}

inline void modify(int fa, int l, int r, int p, int k){//P这个位置的数改为K 
	if (l == r){
		tree[fa].init(k);
		return;
	}
	int mid = l + r >> 1;
	if (p <= mid) modify(lson, p, k);
	else modify(rson, p, k);
	push_up(fa);
}

inline node query(int fa, int l, int r, int ql, int qr){
	if (ql <= l && qr >= r){
		return tree[fa];
	}
	int mid = l + r >> 1;
	if (ql <= mid){
		if (mid < qr) return query(lson, ql, qr) + query(rson, ql, qr);
		else return query(lson, ql, qr);
	}
	else return query(rson, ql, qr);
}

signed main(){
	cin >> n >> m;
	for (int i = 1; i <= n; i++)
		cin >> a[i];
	build(root);	
	while (m--){
		int opt, l, r;
		cin >> opt >> l >> r;	
		if (opt == 1){
			cout << query(root, l, r).maxn << "\n";
		}
		else{
			modify(root, l, r);
		}
	}	
	return 0;
}