Implemented binary insertion sort algorithm

binary_insertion_sort.go

@@ -0,0 +1,28 @@
+package algorithms
+
+// BinaryInsertionSort is an implementation of binary insertion sort algorithm.
+// Wikipedia: https://en.wikipedia.org/wiki/Insertion_sort#Variants
+func BinaryInsertionSort(a []int) []int {
+	for i := 1; i < len(a); i++ {
+		v := a[i]
+		low := 0
+		high := i
+
+		for low < high {
+			mid := low + (high-low)/2
+			if v < a[mid] {
+				high = mid
+			} else {
+				low = mid + 1
+			}
+		}
+
+		for j := i; j > low; j-- {
+			a[j] = a[j-1]
+		}
+
+		a[low] = v
+	}
+
+	return a
+}

binary_insertion_sort_test.go

@@ -0,0 +1,18 @@
+package algorithms
+
+import (
+	"testing"
+)
+
+func TestBinaryInsertionSort(t *testing.T) {
+	testSort(t, BinaryInsertionSort,
+		[]int{5, 3, 1, 4, 2},
+		[]int{1, 2, 3, 4, 5},
+	)
+}
+
+func BenchmarkBinaryInsertionSort(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		BinaryInsertionSort(unsortedArray())
+	}
+}

insertion_sort_test.go

@@ -5,21 +5,21 @@ import (
 )
 
 func TestInsertionSort(t *testing.T) {
-	testInsertionSort(t, InsertionSort,
+	testSort(t, InsertionSort,
 		[]int{5, 3, 1, 4, 2},
 		[]int{1, 2, 3, 4, 5},
 	)
 }
 
 func TestInsertionSortOptimized(t *testing.T) {
-	testInsertionSort(t, InsertionSortOptimized,
+	testSort(t, InsertionSortOptimized,
 		[]int{5, 3, 1, 4, 2},
 		[]int{1, 2, 3, 4, 5},
 	)
 }
 
 func TestInsertionSortOptimizedTwoItems(t *testing.T) {
-	testInsertionSort(t, InsertionSortOptimized,
+	testSort(t, InsertionSortOptimized,
 		[]int{2, 1},
 		[]int{1, 2},
 	)
@@ -36,30 +36,3 @@ func BenchmarkInsertionSortOptimized(b *testing.B) {
 		InsertionSortOptimized(unsortedArray())
 	}
 }
-
-func testInsertionSort(t *testing.T, sortFun func([]int) []int, a, exp []int) {
-	s := sortFun(a)
-	if len(s) != len(exp) {
-		t.Fatal("Array sizes don't match")
-	}
-	for i := 0; i < len(exp); i++ {
-		if s[i] != exp[i] {
-			t.Fatalf("Expected sorted array to equal %v, got %v", exp, s)
-		}
-	}
-}
-
-func unsortedArray() []int {
-	return []int{
-		57, 64, 83, 25, 26, 10, 55, 22, 76, 61,
-		28, 77, 56, 32, 63, 17, 91, 20, 58, 16,
-		1, 51, 88, 82, 24, 70, 81, 35, 49, 39,
-		89, 30, 46, 6, 41, 19, 43, 67, 53, 97,
-		65, 37, 13, 23, 29, 69, 0, 73, 9, 59,
-		96, 34, 66, 79, 27, 14, 40, 80, 98, 2,
-		5, 45, 50, 4, 85, 18, 86, 7, 87, 31,
-		95, 47, 68, 36, 15, 48, 8, 92, 11, 74,
-		78, 52, 44, 42, 54, 84, 12, 21, 38, 99,
-		72, 33, 71, 93, 60, 62, 90, 94, 3, 75,
-	}
-}

sort_test.go

@@ -0,0 +1,32 @@
+package algorithms
+
+import (
+	"testing"
+)
+
+func testSort(t *testing.T, sortFun func([]int) []int, a, exp []int) {
+	s := sortFun(a)
+	if len(s) != len(exp) {
+		t.Fatal("Array sizes don't match")
+	}
+	for i := 0; i < len(exp); i++ {
+		if s[i] != exp[i] {
+			t.Fatalf("Expected sorted array to equal %v, got %v", exp, s)
+		}
+	}
+}
+
+func unsortedArray() []int {
+	return []int{
+		57, 64, 83, 25, 26, 10, 55, 22, 76, 61,
+		28, 77, 56, 32, 63, 17, 91, 20, 58, 16,
+		1, 51, 88, 82, 24, 70, 81, 35, 49, 39,
+		89, 30, 46, 6, 41, 19, 43, 67, 53, 97,
+		65, 37, 13, 23, 29, 69, 0, 73, 9, 59,
+		96, 34, 66, 79, 27, 14, 40, 80, 98, 2,
+		5, 45, 50, 4, 85, 18, 86, 7, 87, 31,
+		95, 47, 68, 36, 15, 48, 8, 92, 11, 74,
+		78, 52, 44, 42, 54, 84, 12, 21, 38, 99,
+		72, 33, 71, 93, 60, 62, 90, 94, 3, 75,
+	}
+}