segment_tree.cpp

#include <bits/stdc++.h>
 
using namespace std;
 
int const N = 1e5 + 1;
int n, m, a[N], type, s, e, t, v, seg[N * 4];
 
void build(int at, int l, int r) {
	if(l == r) {
		seg[at] = a[l];
		return;
	}
 
	int m = (l + r) / 2;
	build(at * 2, l, m);
	build(at * 2 + 1, m + 1, r);
	seg[at] = seg[at * 2] + seg[at * 2 + 1];
}
 
int get(int at, int l, int r) {
	if(l > e || r < s)
		return 0;
 
	if(l >= s && r <= e)
		return seg[at];
 
	int m = (l + r) / 2;
	return get(at * 2, l, m) + get(at * 2 + 1, m + 1, r);
}
 
void update(int at, int l, int r) {
	if(t < l || t > r)
		return;
 
	if(l == r) {
		seg[at] = v;
		return;
	}
 
	int m = (l + r) / 2;
	update(at * 2, l, m);
	update(at * 2 + 1, m + 1, r);
	seg[at] = seg[at * 2] + seg[at * 2 + 1];
}
 
int main() {
#ifndef ONLINE_JUDGE
	freopen("input.in", "r", stdin);
#endif
 
	scanf("%d", &n);
 
	for (int i = 1; i <= n; ++i) {
		scanf("%d", a + i);
	}
 
	build(1, 1, n);
 
	scanf("%d", &m);
 
	for (int i = 0; i < m; ++i) {
		scanf("%d", &type);
 
		if(type == 1) {
			scanf("%d %d", &s, &e);
			printf("%d\n", get(1, 1, n));
		} else {
			scanf("%d %d", &t, &v);
			update(1, 1, n);
		}
	}
 
	return 0;
}