线段树——区间和

#include <bits/stdc++.h>
using namespace std;
inline int read()
{
	char ch;
	while ((ch = getchar()) < '0'&&ch > '9');
	int res = ch - 48;
	while ((ch = getchar()) >= '0'&&ch < '9')
		res = res * 10 + ch - 48;
	return res;
}
const int N = 1e5 + 5;
int n, m;
long long sum[N * 4];
void change(int k, int l, int r, int p, int v)
{
	if (r<p || l>p)return;
	if (l == r && l == p)
	{
		sum[k] += v;
		return;
	}
	int mid = (l + r) / 2;
	change(k * 2, l, mid, p, v);
	change(k * 2 + 1, mid + 1, r, p, v);
	sum[k] = sum[k * 2] + sum[k * 2 + 1];
}
long long query(int k, int l, int r, int x, int y)
{
	if (y<l || x>r)return 0;
	if (l >= x && r <= y)return sum[k];
	int mid = (l + r) / 2;
	long long res = 0;
	res = query(k * 2, l, mid, x, y);
	res += query(k * 2 + 1, mid + 1, r, x, y);
	return res;
}
int main()
{
	n = read(), m = read();
	for (int i = 1; i < m; i++)
	{
		int k = read(), l = read(), r = read();
		//k = 0表示将a[l]加上r,若k = 1表示询问[l,r]的区间和
		if (k == 0)change(1, 1, n, l, r);
		else printf("%lld\n", query(1, 1, n, l, r));
	}
	return 0;
}

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转载自blog.csdn.net/waterboy_cj/article/details/81532350