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pub fn repeated_products(
n: usize,
k: usize,
) -> Vec<Vec<usize>> {
if n == 0 {
assert!(k == 0);
}
let mut res = vec![];
fn dfs(
n: usize,
k: usize,
res: &mut Vec<Vec<usize>>,
a: &mut Vec<usize>,
) {
if a.len() == k {
res.push(a.to_vec());
return;
}
for x in 0..n {
a.push(x);
dfs(n, k, res, a);
a.pop();
}
}
dfs(n, k, &mut res, &mut vec![]);
res
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
let res = repeated_products(3, 3);
assert_eq!(
res,
[
[0, 0, 0],
[0, 0, 1],
[0, 0, 2],
[0, 1, 0],
[0, 1, 1],
[0, 1, 2],
[0, 2, 0],
[0, 2, 1],
[0, 2, 2],
[1, 0, 0],
[1, 0, 1],
[1, 0, 2],
[1, 1, 0],
[1, 1, 1],
[1, 1, 2],
[1, 2, 0],
[1, 2, 1],
[1, 2, 2],
[2, 0, 0],
[2, 0, 1],
[2, 0, 2],
[2, 1, 0],
[2, 1, 1],
[2, 1, 2],
[2, 2, 0],
[2, 2, 1],
[2, 2, 2]
]
);
}
}