Add Zeckendorf in Rust (#5342)

Author: rzuckerm

archive/r/rust/zeckendorf.rs

@@ -0,0 +1,69 @@
+use std::cmp::PartialOrd;
+use std::env::args;
+use std::ops::{Add, SubAssign};
+use std::process::exit;
+use std::str::FromStr;
+
+fn usage() -> ! {
+    println!("Usage: please input a non-negative integer");
+    exit(0);
+}
+
+fn parse_int<T: FromStr>(s: &str) -> Result<T, <T as FromStr>::Err> {
+    s.trim().parse::<T>()
+}
+
+fn get_fibonacci_values<T>(value: T) -> Vec<T> 
+where 
+    T: Add<Output = T> + PartialOrd + From<u8> + Copy 
+{
+    let mut fibs = vec![];
+    let mut a: T = T::from(1);
+    let mut b: T = T::from(2);
+    while a <= value {
+        fibs.push(a);
+        (a, b) = (b, a + b);
+    }
+
+    fibs
+}
+
+fn get_zeckendorf_values<T>(value: T) -> Vec<T>
+where 
+    T: Add<Output = T> + SubAssign + PartialOrd + From<u8> + Copy 
+{
+    let fibs = get_fibonacci_values(value);
+    let mut zecks = vec![];
+    let mut n = (fibs.len() as i32) - 1;
+    let mut remaining = value;
+    while n >= 0 && remaining > T::from(0) {
+        let f = fibs[n as usize];
+        if remaining >= f {
+            zecks.push(f);
+            remaining -= f;
+            n -= 2;
+        } else {
+            n -= 1;
+        }
+    }
+
+    zecks
+}
+
+fn main() {
+    let mut args = args().skip(1);
+
+    // Exit if 1st command-line argument not an integer
+    let input_num: i32 = args
+        .next()
+        .and_then(|s| parse_int(&s).ok())
+        .unwrap_or_else(|| usage());
+
+    // Exit if value is negative
+    if input_num < 0 {
+        usage();
+    }
+
+    let zecks = get_zeckendorf_values::<i32>(input_num);
+    println!("{:?}", zecks);
+}