整数分块

整数分块

计算$\sum_{n=1}^{n=d} \lfloor \frac{d}{n} \rfloor$,将n分成多个块,

使得每个块$[left<=i<=right], \frac{d}{i}=同一个数$

struct node
{
    int left,right,num;
};
node a[10000];
int top=0;
for (int l = 1, r; l <= d; l = r + 1)
{
    r = d / (d / l);
    a[++top].left = l, a[top].right = r, a[top].num = x / l;
}