Add bucket_sort for arrays.

src/main.rs

@@ -1,8 +1,10 @@
 mod bst;
 mod stack;
+mod sort;
 
 use bst::BinarySearchTree;
 use stack::Stack;
+use sort::bucket_sort;
 
 struct Greeter {
     greeting: &'static str,
@@ -62,4 +64,15 @@ fn main() {
     unsafe {
         print_num(find_result);
     }
+
+    // linear bucket sort
+    let items = [3, 2, 1, 1, 2, 3, 4];
+    println!("before sort: {:?}", items);
+
+    let sorted = bucket_sort(&items);
+    println!("sorted: {:?}", sorted);
+
+    let some_chars = ['a', 'b', 'c', 'c', 'a', 'b', 'd'];
+    let sorted_chars = bucket_sort(&some_chars);
+    println!("sorted chars: {:?}", sorted_chars);
 }

src/sort.rs

@@ -0,0 +1,22 @@
+use std::collections::BTreeMap;
+
+pub fn bucket_sort<T: Ord + Default + Copy, const SIZE: usize>(to_sort: &[T; SIZE]) -> [T; SIZE] {
+    // sort into buckets
+    let mut buckets = BTreeMap::new();
+    for item in to_sort {
+        buckets.entry(item).and_modify(|count| *count += 1).or_insert(1);
+    }
+
+    // Create new array, copying items to new array
+    let mut result: [T; SIZE] = [T::default(); SIZE];
+    let mut pos = 0;
+    for (item, count) in buckets {
+        let mut i = 0;
+        while i < count {
+            result[pos] = *item;
+            i += 1;
+            pos += 1;
+        }
+    }
+    result
+}