segtree.cpp

#include <bits/stdc++.h>
using namespace std;

const int maxn = 1e5;

#define LEFT (2*node)
#define RIGHT ((2*node) + 1)
#define MID ((l + r)/2)

int tree[3*maxn], v[maxn];

int op(int a, int b)
{
	return a + b;
}

void build(int node, int l, int r)
{
	if(l == r) tree[node] = v[l];

	else
	{
		build(LEFT, l, MID);
		build(RIGHT, MID + 1, r);

		tree[node] = op(tree[LEFT], tree[RIGHT]);
	}
}

int query(int node, int l, int r, int a, int b)
{
	if(a > r or b < l) return 0;

	if(a <= l and r <= b) return tree[node];

	int q1 = query(LEFT, l, MID, a, b);
	int q2 = query(RIGHT, MID + 1, r, a, b);

	return q1 + q2;
}

void update(int node, int l, int r, int pos, int val)
{
	if(l == r) tree[node] = v[l] = val;

	else
	{
		if(pos <= MID) update(LEFT, l, MID, pos, val);
		else update(RIGHT, MID + 1, r, pos, val);

		tree[node] = op(tree[LEFT], tree[RIGHT]);
	}
}

int main()
{
	int n, q;

	cin >> n >> q;

	for(int i = 1; i <= n; i++)
		cin >> v[i];

	build(1, 1, n);

	while(q--)
	{
		int op, a, b;

		cin >> op >> a >> b;

		if(op == 0)
		{
			cout << query(1, 1, n, a, b) << "\n";
		}
		else
		{
			update(1, 1, n, a, b);
			for(int i = 1; i <= n; i++)
				cout << v[i] << " \n"[i == n];
		}
	}
}

Thank you!