impl Solution {
    pub fn count_arrangement(n: i32) -> i32 {
        let mut nums: Vec<_> = (1..=n).collect();
        let mut vis: Vec<_> = (0..n).map(|x| false).collect();
        let mut result = vec![];
        Solution::count_arrangement_0(&mut nums, 0, &mut vis, &mut vec![], &mut result);
        return result.len() as i32;
    }

    pub fn count_arrangement_0(arr: &mut Vec<i32>, idx: usize, vis: &mut Vec<bool>, collector: &mut Vec<i32>, res: &mut Vec<Vec<i32>>) {
        if collector.len() == arr.len() {
            res.push(collector.clone());
            return;
        }
        for i in 0..arr.len() {
            if vis[i] {
                continue;
            }
            if !(arr[i] % (collector.len() + 1) as i32 == 0 || (collector.len() + 1) as i32 % arr[i] == 0) {
                continue;
            }
            collector.push(arr[i]);
            vis[i] = true;
            Solution::count_arrangement_0(arr, idx + 1, vis, collector, res);
            collector.pop();
            vis[i] = false;
        }
    }
}