Yekong's Blog

let mut content = File::open("input")?;
let mut codes = String::new();
content.read_to_string(&mut codes)?;
let batteries = codes.trim().split_whitespace().collect::<Vec<&str>>();

let mut total = 0;

for battery in batteries {
    let mut first = 0;
    let mut number = 0;
    let mut last_biggest_pos = 100;
    let mut pos = 0;
    let len = battery.len();
    
    // loop 12 times as second question requires the biggest number with 12 digits
    for j in (1..=12).rev() {
        for i in pos..len {
            // Convert current character to digit
            let num: i64 = battery.chars().nth(i).unwrap().to_digit(10).unwrap() as i64;
            
            // Check if current number is greater than or equal to the first number
            // and if the remaining length is greater than or equal to the current digit positions
            // we need to ensure that we can get enough digits from the remaining positions
            if max(num, first) == num && len - i >= j {
                if max(num, first) != first {
                    // Only record if the current number is greater than the first number
                    // make sure next loop won't skip the same number
                    // SAMPLE: 81818181223412323
                    // the biggest number should start with 888822.....
                    last_biggest_pos = i + 1;
                }
                first = num;
            }
            // Check if the remaining length is less than the current digit positions
            if len - i < j {
                break;
            }
        }
        if j != 1 {
            let base: i64 = 10;
            number += first * base.pow((j - 1) as u32); // join the number
            first = 0; // Reset first to 0 for the next iteration
        } else {
            number += first;
        }
        pos = last_biggest_pos;
    }
    total += number;
}

println!("Total: {}", total);

// MAX FUNCTION
fn max(a: i64, b: i64) -> i64 {
    if a > b { a } else { b }
}