Problem:
Score : 300 points

Problem Statement

To make it difficult to withdraw money, a certain bank allows its customers to withdraw only one of the following amounts in one operation:

1 yen (the currency of Japan)

6 yen, 6^2(=36) yen, 6^3(=216) yen, ...

9 yen, 9^2(=81) yen, 9^3(=729) yen, ...

At least how many operations are required to withdraw exactly N yen in total?

It is not allowed to re-deposit the money you withdrew.

Constraints

1 \leq N \leq 100000

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

If at least x operations are required to withdraw exactly N yen in total, print x.

Sample Input 1

127

Sample Output 1

4

By withdrawing 1 yen, 9 yen, 36(=6^2) yen and 81(=9^2) yen, we can withdraw 127 yen in four operations.

Sample Input 2

3

Sample Output 2

3

By withdrawing 1 yen three times, we can withdraw 3 yen in three operations.

Sample Input 3

44852

Sample Output 3

16

Solution in Rust (1.15.1) (judge verdict: Accepted)

use std::thread;

/// ローカル環境なら _in.txt から入力を受ける
fn read_input() -> String {
    use std::fs::File;
    use std::io::Read;
    let mut s = String::new();
    match option_env!("LOCAL") {
        Some(_) => File::open("src/_in.txt")
            .expect("File not found")
            .read_to_string(&mut s)
            .unwrap(),
        None => std::io::stdin().read_to_string(&mut s).unwrap(),
    };
    s
}

static mut MEMO: [i32; 100010] = [-1; 100010];

unsafe fn solve(n: i32) -> i32 {
    if n <= 0 {
        return 0;
    }
    if MEMO[n as usize] >= 0 {
        return MEMO[n as usize];
    }

    let mut ret = vec![];

    ret.push(solve(n - 1) + 1);
    let mut d = 9;
    while n - d >= 0 {
        ret.push(solve(n - d) + 1);
        d *= 9
    }
    let mut d = 6;
    while n - d >= 0 {
        ret.push(solve(n - d) + 1);
        d *= 6
    }

    MEMO[n as usize] = *ret.iter().min().unwrap();
    MEMO[n as usize]
}

fn main() {
    thread::Builder::new()
        .stack_size(64 * 1024 * 1024) // 64MB
        .spawn(|| {
            let s = read_input();
            let mut ws = s.split_whitespace();
            let in_n: i32 = ws.next().unwrap().parse().unwrap();
            let ans = unsafe { solve(in_n) };
            println!("{:?}", ans);
        })
        .unwrap()
        .join()
        .unwrap();
}