Moved nth_lex out of struct impl

src/combination.rs

@@ -16,26 +16,11 @@ fn binomial(n: usize, k: usize) -> usize {
     }
 }
 
-#[derive(Clone)]
-pub struct Combinator<T: Clone + Ord> {
-    pub current: Vec<T>,
-    pub k: usize,
-    idx: usize,
-}
-
-impl<T: Clone + Ord> Combinator<T> {
-    pub fn new(elements: Vec<T>, k: usize) -> Result<Combinator<T>, Box<dyn Error>> {
-        if k > elements.len() || k == 0 {
-            return Err(Box::from("Out of bounds"));
-        }
-        Ok(Self {
-            current: elements,
-            k,
-            idx: 0,
-        })
-    }
-
-    pub fn nth_lex(mut elements: Vec<T>, k: usize, nth: usize) -> Result<Vec<T>, Box<dyn Error>> {
+pub fn nth_lex<T: Clone + Ord>(
+    mut elements: Vec<T>,
+    k: usize,
+    nth: usize,
+) -> Result<Vec<T>, Box<dyn Error>> {
     elements.sort();
     let num_elements = elements.len();
     let num_combinations = binomial(num_elements, k);
@@ -64,6 +49,25 @@ impl<T: Clone + Ord> Combinator<T> {
         i += 1;
     }
     Ok(comb)
+}
+
+#[derive(Clone)]
+pub struct Combinator<T: Clone + Ord> {
+    pub current: Vec<T>,
+    pub k: usize,
+    idx: usize,
+}
+
+impl<T: Clone + Ord> Combinator<T> {
+    pub fn new(elements: Vec<T>, k: usize) -> Result<Combinator<T>, Box<dyn Error>> {
+        if k > elements.len() || k == 0 {
+            return Err(Box::from("Out of bounds"));
+        }
+        Ok(Self {
+            current: elements,
+            k,
+            idx: 0,
+        })
     }
 }
 

src/permutation.rs

@@ -8,33 +8,19 @@ fn factorial(num: usize) -> usize {
     fact
 }
 
-#[derive(Clone)]
-pub struct Permutator<T: Copy + Ord> {
-    pub current: Vec<T>,
-    idx: usize,
-}
-
-impl<T: Copy + Ord> Permutator<T> {
-    pub fn new(elements: Vec<T>) -> Self {
-        Self {
-            current: elements,
-            idx: 0,
-        }
-    }
-
-    /// Explanation
-    ///
-    /// there are 10! possible permutations
-    /// for each first number there are 9!, for each first 2 numbers 8!, etc.
-    /// we check how many times we have 9! permutations before we're over 1_000_000
-    /// aka. 1000000 / 9!
-    /// we take the remainder and check how many times we have 8! before we?re over it
-    /// (1000000 % 9!) 8!
-    /// etc.
-    /// every iteration we remove the digit by the idx from the original permutation
-    /// we only check for 999999 permutations because we already have the first one
-    ///
-    pub fn nth_lex(mut digits: Vec<T>, nth: usize) -> Result<Vec<T>, Box<dyn Error>> {
+/// Explanation
+///
+/// there are 10! possible permutations
+/// for each first number there are 9!, for each first 2 numbers 8!, etc.
+/// we check how many times we have 9! permutations before we're over 1_000_000
+/// aka. 1000000 / 9!
+/// we take the remainder and check how many times we have 8! before we?re over it
+/// (1000000 % 9!) 8!
+/// etc.
+/// every iteration we remove the digit by the idx from the original permutation
+/// we only check for 999999 permutations because we already have the first one
+///
+pub fn nth_lex<T: Clone + Ord>(mut digits: Vec<T>, nth: usize) -> Result<Vec<T>, Box<dyn Error>> {
     digits.sort();
     if nth == 1 {
         return Ok(digits);
@@ -48,14 +34,28 @@ impl<T: Copy + Ord> Permutator<T> {
     for idx in 1..=digits.len() {
         let permutations = remainder / factorial(num_unique_digits - idx);
         remainder %= factorial(num_unique_digits - idx);
-            perm.push(digits[permutations]);
+        perm.push(digits[permutations].clone());
         digits.remove(permutations);
     }
     Ok(perm)
+}
+
+#[derive(Clone)]
+pub struct Permutator<T: Clone + Ord> {
+    pub current: Vec<T>,
+    idx: usize,
+}
+
+impl<T: Clone + Ord> Permutator<T> {
+    pub fn new(elements: Vec<T>) -> Self {
+        Self {
+            current: elements,
+            idx: 0,
+        }
     }
 }
 
-impl<T: Copy + Ord> Iterator for Permutator<T> {
+impl<T: Clone + Ord> Iterator for Permutator<T> {
     type Item = Vec<T>;
     /// Returns the next permutation and changes the current permutation to it
     /// This operation wraps around
@@ -73,7 +73,7 @@ impl<T: Copy + Ord> Iterator for Permutator<T> {
         for idx in 1..=digits.len() {
             let permutations = remainder / factorial(num_unique_digits - idx);
             remainder %= factorial(num_unique_digits - idx);
-            perm.push(digits[permutations]);
+            perm.push(digits[permutations].clone());
             digits.remove(permutations);
         }
         self.idx += 1;