feat: add comb sort (rust-lang#231)

* Add comb sort

* Add comb sort to README.

Co-authored-by: imp <imp07@qq.com>

Author: Wafelack

README.md

@@ -20,6 +20,7 @@ RESTART BUILD
 - [x] [Selection](./src/sorting/selection_sort.rs)
 - [x] [Shell](./src/sorting/shell_sort.rs)
 - [x] [Stooge](./src/sorting/stooge_sort.rs)
+- [x] [Comb](./src/sorting/comb_sort.rs)
 
 ## Graphs
 

src/sorting/comb_sort.rs

@@ -0,0 +1,45 @@
+pub fn comb_sort<T: Ord>(arr: &mut [T]) {
+    let mut gap = arr.len();
+    let shrink = 1.3;
+    let mut sorted = false;
+
+    while !sorted {
+        gap = (gap as f32 / shrink).floor() as usize;
+        if gap <= 1 {
+            gap = 1;
+            sorted = true;
+        }
+        for i in 0..arr.len() - gap {
+            let j = i + gap;
+            if arr[i] > arr[j] {
+                arr.swap(i, j);
+                sorted = false;
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn descending() {
+        //descending
+        let mut ve1 = vec![6, 5, 4, 3, 2, 1];
+        comb_sort(&mut ve1);
+        for i in 0..ve1.len() - 1 {
+            assert!(ve1[i] <= ve1[i + 1]);
+        }
+    }
+
+    #[test]
+    fn ascending() {
+        //pre-sorted
+        let mut ve2 = vec![1, 2, 3, 4, 5, 6];
+        comb_sort(&mut ve2);
+        for i in 0..ve2.len() - 1 {
+            assert!(ve2[i] <= ve2[i + 1]);
+        }
+    }
+}

src/sorting/mod.rs

@@ -1,5 +1,6 @@
 mod bubble_sort;
 mod cocktail_shaker_sort;
+mod comb_sort;
 mod counting_sort;
 mod heap_sort;
 mod insertion_sort;
@@ -13,6 +14,7 @@ mod stooge_sort;
 
 pub use self::bubble_sort::bubble_sort;
 pub use self::cocktail_shaker_sort::cocktail_shaker_sort;
+pub use self::comb_sort::comb_sort;
 pub use self::counting_sort::counting_sort;
 pub use self::counting_sort::generic_counting_sort;
 pub use self::heap_sort::heap_sort;