Enhance Fibonacci-Lucas Computation & Optimize Code Efficiency

src/main.rs

@@ -4,9 +4,32 @@ use malachite::{
     base::num::{
         arithmetic::traits::Square,
         basic::traits::{One, Two, Zero},
+        conversion::traits::{FromSciString, FromStringBase},
     },
 };
-use std::{io, time::Instant};
+use std::{env, io, io::Write, time::Instant};
+
+fn input(prompt: &str) -> anyhow::Result<String> {
+    print!("{}", prompt);
+    io::stdout().flush().unwrap();
+    let mut n = String::new();
+    io::stdin().read_line(&mut n)?;
+    Ok(n.trim().to_string())
+}
+
+fn starts_with(string: &str, prefixes: &[&str]) -> bool {
+    prefixes.iter().any(|&prefix| string.starts_with(prefix))
+}
+
+fn bigint(n: String) -> anyhow::Result<Integer> {
+    let parsed = if starts_with(&n, &["0x", "0X"]) {
+        Integer::from_string_base(16, &n[2..])
+    } else {
+        Integer::from_sci_string(&n)
+    };
+
+    parsed.ok_or_else(|| anyhow!("Invalid integer format"))
+}
 
 const FIVE: Integer = Integer::const_from_unsigned(5);
 
@@ -23,7 +46,7 @@ fn fib_luc(n: Integer) -> (Integer, Integer) {
 
     if &n & &Integer::ONE == 1 {
         let (fib, luc) = fib_luc(n - Integer::ONE);
-        return (&fib + &luc >> 1, FIVE * &fib + &luc >> 1);
+        return ((&fib + &luc) >> 1, (FIVE * &fib + &luc) >> 1);
     }
 
     let (fib, luc) = fib_luc(&n >> 1);
@@ -34,18 +57,34 @@ fn fib_luc(n: Integer) -> (Integer, Integer) {
 }
 
 fn main() -> anyhow::Result<()> {
-    let mut number = String::new();
-    io::stdin().read_line(&mut number)?;
-    let number = number
-        .trim()
-        .parse::<Integer>()
-        .map_err(|_| anyhow!("unable to parse integer"))?;
+    let args: Vec<String> = env::args().collect();
+    let print_all = args.contains(&"--print".to_string());
+    let print_fib = args.contains(&"--fib".to_string());
+    let print_lucas = args.contains(&"--lucas".to_string());
+
+    // Display description before prompt
+    println!("This program computes the Fibonacci and Lucas numbers of a given integer.");
+
+    let number = bigint(input("Enter a number: ")?)
+        .map_err(|_| anyhow!("Unable to parse integer"))?;
 
     let start = Instant::now();
-    let (fib, _) = fib_luc(number.clone());
+    let (fib, luc) = fib_luc(number.clone());
     let elapsed = start.elapsed();
-    //println!("{}", fib);
-    println!("{:?}", elapsed);
+
+    if print_all {
+        println!("Fibonacci:\t{}", fib);
+        println!("Lucas:\t\t{}", luc);
+    } else {
+        if print_fib {
+            println!("Fibonacci:\t{}", fib);
+        }
+        if print_lucas {
+            println!("Lucas:\t\t{}", luc);
+        }
+    }
+
+    println!("Elapsed time:\t{:?}", elapsed);
 
     Ok(())
 }