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use std::collections::HashMap;
use once_cell::sync::Lazy;
use std::sync::Mutex;
use std::env;
static DIGIT_WEIGHT: Lazy<Mutex<HashMap<i32, i32>>> = Lazy::new(|| {
Mutex::new(HashMap::new())
});
fn calculate_digit_weight(num: i32) -> i32 {
let mut cache = DIGIT_WEIGHT.lock().unwrap();
if let Some(&cached) = cache.get(&num) {
return cached;
}
let mut n = num;
let mut count = 0;
while n > 9 {
count += 1;
let mut tmp = 1;
for digit in n.to_string().chars() {
tmp *= digit.to_digit(10).unwrap() as i32;
}
n = tmp;
}
cache.insert(num, count);
count
}
fn persistence_sort(array: &Vec<i32>) -> Vec<i32> {
let mut sorted_array = array.clone();
sorted_array.sort_by(|a, b| {
let weight_a = calculate_digit_weight(*a);
let weight_b = calculate_digit_weight(*b);
if weight_a != weight_b {
weight_a.cmp(&weight_b)
} else {
a.cmp(b)
}
});
sorted_array
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_calculate_digit_weight() {
assert_eq!(calculate_digit_weight(9), 0);
assert_eq!(calculate_digit_weight(15), 1);
assert_eq!(calculate_digit_weight(99), 2);
assert_eq!(calculate_digit_weight(12347), 4);
}
#[test]
fn test_persistence_sort() {
let test_cases = vec![
(vec![15, 99, 1, 34], vec![1, 15, 34, 99]),
(vec![50, 25, 33, 22], vec![22, 33, 50, 25]),
(vec![12347, 2347, 347, 47, 7], vec![7, 47, 347, 2347, 12347]),
];
for (input, want) in test_cases {
let output = persistence_sort(&input);
assert_eq!(output, want);
}
}
}
fn main() {
// Get command-line arguments, excluding the program name
let args: Vec<String> = env::args().collect();
// Create a Vec<i32> by parsing the command-line arguments
let in_vec: Vec<i32> = args
.iter()
.skip(1) // Skip the first argument, which is the program name
.filter_map(|arg| arg.parse().ok())
.collect();
// Print the resulting Vec<i32>
let out_vec: Vec<i32> = persistence_sort(&in_vec);
println!(" Input: {:?}", in_vec);
println!("Running Sum: {:?}", out_vec);
}
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