cpp算法-树状数组

int tree[2000010];

int (int k)
{
    return k & -k;
}

void add(int x, int k)
{
    while (x <= n)
    {
        tree[x] += k;
        x += lowbit(x);
    }
}

int sum(int x)
{
    int ans = 0;
    while (x != 0)
    {
        ans += tree[x];
        x -= lowbit(x);
    }
    return ans;
}