WA
#include<bits/stdc++.h>
#define ll long long
#define maxn 500005
using namespace std;
ll a[maxn], w[maxn << 2], lzy[maxn << 2];
void pushup(int u){
	w[u] = w[u * 2] + w[u * 2 + 1];
}
void build(int u, int l, int r){
	if(l == r){
		w[u] = a[l];
		return;
	}
	int m = (l + r) >> 1;
	build(u * 2, l, m);
	build(u * 2 + 1, m + 1, r);
	pushup(u);
}
ll query1(int u, int l, int r, int p){
	if(l == r) return w[u];
	else{
		int m = (l + r) >> 1;
		if(m >= p) return query1(u * 2, l, m, p);
		else return query1(u * 2 + 1, m + 1, r, p);
	}
}
void update1(int u, int l, int r, int p, ll x){
	if(l == r) w[u] = x;
	else{
		int m = (l + r) >> 1;
		if(m >= p) update1(u * 2, l, m, p, x);
		else update1(u * 2 + 1, m + 1, r, p, x);
	}
	pushup(u);
}
bool inRange(int l, int r, int L, int R){
	return (L <= l) && (r <= R);
}
bool outofRange(int l, int r, int L, int R){
	return (l > R) || (r < L);
}
void maketag(int u, int len, ll x){
	lzy[u] += x;
	w[u] += len * x;
}
void pushdown(int u, int l, int r){
	int m = (l + r) >> 1;
	maketag(u * 2, m - l + 1, lzy[u]);
	maketag(u * 2 + 1, r - m, lzy[u]);
	lzy[u] = 0;
}
ll query(int u, int l, int r, int L, int R){
	if(inRange(l, r, L, R)) return w[u];
	else if(outofRange(l, r, L, R)) return 0;
	else{
		int m = (l + r) >> 1;
		pushdown(u, l, r);
		return query(u * 2, l, m, L, R) + query(u * 2 + 1, m + 1, r, L, R);
	}
}
void update(int u, int l, int r, int L, int R, ll x){
	if(inRange(l, r, L, R)) maketag(u, r - l + 1, x);
	else if(!outofRange(l, r, L, R)){
		int m = (l + r) >> 1;
		pushdown(u, l, r);
		update(u * 2, l, m, L, R, x);
		update(u * 2 + 1, m + 1, r, L, R, x);
		pushup(u);
	}
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n, m;
	cin >> n >> m;
	for(int i = 1; i <= n; i++) cin >> a[i];
	build(1, 1, n);
	while(m--){
		int op;
		cin >> op;
		if(!(op ^ 1)){
			int x, y, k;
			cin >> x >> y >> k;
			update(1, 1, n, x, y, k);
		}else{
			int x;
			cin >> x;
			cout << query1(1, 1, n, x) << '\n';
		}
	}
}

AC代码
#include<bits/stdc++.h>
#define ll long long
#define maxn 100005
using namespace std;
ll a[maxn], w[maxn << 2], lzy[maxn << 2];
void pushup(int u){
	w[u] = w[u * 2] + w[u * 2 + 1];
}
void build(int u, int l, int r){
	if(l == r){
		w[u] = a[l];
		return;
	}
	int m = (l + r) >> 1;
	build(u * 2, l, m);
	build(u * 2 + 1, m + 1, r);
	pushup(u);
}
ll query1(int u, int l, int r, int p){
	if(l == r) return w[u];
	else{
		int m = (l + r) >> 1;
		if(m >= p) return query1(u * 2, l, m, p);
		else return query1(u * 2 + 1, m + 1, r, p);
	}
}
void update1(int u, int l, int r, int p, ll x){
	if(l == r) w[u] = x;
	else{
		int m = (l + r) >> 1;
		if(m >= p) update1(u * 2, l, m, p, x);
		else update1(u * 2 + 1, m + 1, r, p, x);
	}
	pushup(u);
}
bool inRange(int l, int r, int L, int R){
	return (L <= l) && (r <= R);
}
bool outofRange(int l, int r, int L, int R){
	return (l > R) || (r < L);
}
void maketag(int u, int len, ll x){
	lzy[u] += x;
	w[u] += len * x;
}
void pushdown(int u, int l, int r){
	int m = (l + r) >> 1;
	maketag(u * 2, m - l + 1, lzy[u]);
	maketag(u * 2 + 1, r - m, lzy[u]);
	lzy[u] = 0;
}
ll query(int u, int l, int r, int L, int R){
	if(inRange(l, r, L, R)) return w[u];
	else if(outofRange(l, r, L, R)) return 0;
	else{
		int m = (l + r) >> 1;
		pushdown(u, l, r);
		return query(u * 2, l, m, L, R) + query(u * 2 + 1, m + 1, r, L, R);
	}
}
void update(int u, int l, int r, int L, int R, ll x){
	if(inRange(l, r, L, R)) maketag(u, r - l + 1, x);
	else if(!outofRange(l, r, L, R)){
		int m = (l + r) >> 1;
		pushdown(u, l, r);
		update(u * 2, l, m, L, R, x);
		update(u * 2 + 1, m + 1, r, L, R, x);
		pushup(u);
	}
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n, m;
	cin >> n >> m;
	for(int i = 1; i <= n; i++) cin >> a[i];
	build(1, 1, n);
	while(m--){
		int op;
		cin >> op;
		if(!(op ^ 1)){
			int x, y, k;
			cin >> x >> y >> k;
			update(1, 1, n, x, y, k);
		}else{
			int x, y;
			cin >> x >> y;
			cout << query(1, 1, n, x, y) << '\n';
		}
	}
}