From 4edf2dd20b300c27dcc96829e262aedcd438291a Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Sun, 12 Jul 2020 11:35:03 +0100
Subject: have selection sort

---
 Makefile               |  4 ++++
 ds/comparer.go         |  9 +++++++++
 ds/integer.go          | 25 +++++++++++++++++++++++++
 main.go                | 14 ++++++++++++++
 sort/selection.go      | 24 ++++++++++++++++++++++++
 sort/selection_test.go | 12 ++++++++++++
 6 files changed, 88 insertions(+)
 create mode 100644 Makefile
 create mode 100644 ds/comparer.go
 create mode 100644 ds/integer.go
 create mode 100644 main.go
 create mode 100644 sort/selection.go
 create mode 100644 sort/selection_test.go

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..6883353
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,4 @@
+all:
+	go build
+test:
+	go run main.go
diff --git a/ds/comparer.go b/ds/comparer.go
new file mode 100644
index 0000000..737ad1b
--- /dev/null
+++ b/ds/comparer.go
@@ -0,0 +1,9 @@
+package ds
+
+type Comparer interface {
+	LowerThan(a Comparer) bool
+	HigherThan(a Comparer) bool
+	Equals(a Comparer) bool
+}
+
+type CompareList []Comparer
diff --git a/ds/integer.go b/ds/integer.go
new file mode 100644
index 0000000..69ee0aa
--- /dev/null
+++ b/ds/integer.go
@@ -0,0 +1,25 @@
+package ds
+
+import "math/rand"
+
+type Integer int
+
+func RandomIntegers(length, max int) []Comparer {
+	a := make([]Comparer, length)
+	for i := 0; i < length; i++ {
+		a[i] = Integer(rand.Intn(max))
+	}
+	return a
+}
+
+func (i Integer) LowerThan(j Comparer) bool {
+	return i < j.(Integer)
+}
+
+func (i Integer) HigherThan(j Comparer) bool {
+	return i > j.(Integer)
+}
+
+func (i Integer) Equals(j Comparer) bool {
+	return i == j.(Integer)
+}
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..aa4a82f
--- /dev/null
+++ b/main.go
@@ -0,0 +1,14 @@
+package main
+
+import (
+	"algorithms/ds"
+	"algorithms/sort"
+	"fmt"
+)
+
+func main() {
+	fmt.Println("Hello to Algorithms Playground!")
+	a := ds.RandomIntegers(100, 1000)
+	fmt.Printf("Random: %v\n", a)
+	fmt.Printf("Sorted: %v\n", sort.Selection(a))
+}
diff --git a/sort/selection.go b/sort/selection.go
new file mode 100644
index 0000000..e2a774c
--- /dev/null
+++ b/sort/selection.go
@@ -0,0 +1,24 @@
+package sort
+
+import (
+	"algorithms/ds"
+)
+
+func Selection(a []ds.Comparer) []ds.Comparer {
+	length := len(a)
+	for i := 0; i < length; i++ {
+		max := i
+		for j := i + 1; j < length; j++ {
+			if a[max].HigherThan(a[j]) {
+				max = j
+			}
+		}
+		if max == i {
+			continue
+		}
+		tmp := a[i]
+		a[i] = a[max]
+		a[max] = tmp
+	}
+	return a
+}
diff --git a/sort/selection_test.go b/sort/selection_test.go
new file mode 100644
index 0000000..3881850
--- /dev/null
+++ b/sort/selection_test.go
@@ -0,0 +1,12 @@
+package sort
+
+import (
+	"algorithms/ds"
+	"testing"
+)
+
+func BenchmarkSelection1000(b *testing.B) {
+	a := ds.RandomIntegers(1000, 1000)
+	b.ResetTimer()
+	Selection(a)
+}
-- 
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