二维树状数组模板

int n,c

;
int lowbit(int x)
{
return x&(-x);
}
int query_sum(int x, int y)
{
int res = 0;
for (int i = x; i > 0; i -= lowbit(i))
{
for (int j = y; j > 0; j -= lowbit(j))
{
res += c[i][j];
}
}
return res;
}

void add(int x, int y, int val)
{
for (int i = x; i <= n; i += lowbit(i))
{
for (int j = y; j <= n; j += lowbit(j))
{
c[i][j] += val;
}
}
}