数あて.rs

use std::collections::HashSet;

fn main() {
    let mut candidate_count = 0;
    for i in 1..100000 {
        if satisfy(i) {
            candidate_count += 1;
            println!("Candidate: {}", i.to_string());
        }
    }
    println!("{}", candidate_count.to_string());
}

fn satisfy(x: i32) -> bool {
    return digits_sum(x) == 22 && digits(x) == 5 && phi(x) == 15;
}

fn digits_sum(x: i32) -> i32 {
    let mut result: i32 = 0;
    let mut x = x;
    while x > 0 {
        result += x % 10;
        x /= 10;
    }
    return result;
}

fn digits(x: i32) -> i32 {
    if x == 0 {
        return 1;
    }
    let mut result: i32 = 0;
    let mut x = x;
    while x > 0 {
        result += 1;
        x /= 10;
    }
    return result;
}

fn phi(x: i32) -> i32 {
    let bound = (x as f64).sqrt().ceil() as i32 + 1;
    let mut dividers = HashSet::new();
    for i in 1..bound {
        if x % i == 0 {
            dividers.insert(i);
            dividers.insert(x / i);
        }
    }
    return dividers.len() as i32;
}