atcoder_nary_exp.rs

mod nary_exp{
    struct NaryExpander{
        n: i64,
        base: i64,
        powered: i64
    }

    impl NaryExpander{
        fn new(n: i64, base: i64) -> NaryExpander{
            let mut powered = (0..).map(|i|{base.pow(i)}).find(|i|{*i > n}).unwrap();
            powered /= base;
            NaryExpander{n: n, base: base, powered: powered}
        }
    }

    impl Iterator for NaryExpander{
        type Item = i64;

        fn next(&mut self) -> Option::<i64>{
            if self.powered <= 0{
                return None;
            }
            let res = self.n / self.powered;
            self.n %= self.powered;
            self.powered /= self.base;
            return Some(res);
        }
    }

    #[test]
    fn test(){
        assert_eq!(NaryExpander::new(765, 10).collect::<Vec<i64>>(), vec![7, 6, 5]);
        assert_eq!(NaryExpander::new(7, 2).collect::<Vec<i64>>(), vec![1, 1, 1]);
    }

}