shuffle function

README.md

@@ -1,2 +1,3 @@
 # algorithms
-My personal implementations of data structure and random algorithms
+
+a lot of problems, with bad solutions

shuffle/shuffle.go

@@ -1,5 +1,25 @@
 package shuffle
 
-func shuffle(arr string) string {
-	return arr
+import (
+	"math/rand"
+	"strings"
+)
+
+// Shuffle returns a shuffled version of the given string
+//
+//		Shuffle("rtfm") -> fmrt
+func Shuffle(arr string) string {
+	var result = make([]string, len(arr))
+
+	for k, v := range strings.Split(arr, "") {
+		j := rand.Intn(len(arr) - 0)
+
+		tmp := v
+
+		result[k] = result[j]
+		result[j] = tmp
+
+	}
+
+	return strings.Join(result, "")
 }

shuffle/shuffle_test.go

@@ -8,21 +8,24 @@ import (
 func TestShuffle(t *testing.T) {
 	assert := assertTest.New(t)
 
-	t.Run("should shuffle string", func(t *testing.T) {
-		payload := "my payload to shuffle"
+	t.Run("should Shuffle string", func(t *testing.T) {
+		payload := "my payload to Shuffle"
 
-		assert.NotEqual(payload, shuffle(payload))
+		assert.NotEqual(payload, Shuffle(payload))
 	})
 
-	t.Run("should shuffle string", func(t *testing.T) {
+	t.Run("should Shuffle string", func(t *testing.T) {
 		payload := "a"
 
-		assert.Equal(payload, shuffle(payload))
+		assert.Equal(payload, Shuffle(payload))
 	})
 
-	t.Run("should shuffle string", func(t *testing.T) {
+	t.Run("should Shuffle string", func(t *testing.T) {
 		payload := "ab"
 
-		assert.Equal(payload, shuffle(payload))
+		result := Shuffle(payload)
+
+		assert.Contains(result, "a")
+		assert.Contains(result, "b")
 	})
 }