merge sort added

.gitignore

@@ -25,3 +25,4 @@ _testmain.go
 
 sorting/bubble_sort
 sorting/selection_sort
+sorting/merge_sort

README.md

@@ -19,6 +19,7 @@ alghoritms
 
   * bubble sort
   * selection sort
+  * merge sort
 
 todo
 ------

sorting/merge_sort.go

@@ -0,0 +1,52 @@
+package main
+
+/*
+ * Merge sort - http://en.wikipedia.org/wiki/Merge_sort
+ */
+
+import "fmt"
+
+import "github.com/IoSync/go-alghoritms"
+
+func Merge(left, right []int) []int {
+    result := make([]int, 0, len(left) + len(right))
+    
+    for len(left) > 0 || len(right) > 0 {
+        if len(left) == 0 {
+            return append(result, right...)
+        }
+        if len(right) == 0 {
+            return append(result, left...)
+        }
+        if left[0] <= right[0] {
+            result = append(result, left[0])
+            left = left[1:]
+        } else {
+            result = append(result, right[0])
+            right = right[1:]
+        }
+    }
+    
+    return result
+}
+
+func MergeSort(arr []int) []int {
+    if len(arr) <= 1 {
+        return arr
+    }
+    
+    middle := len(arr) / 2
+    
+    left := MergeSort(arr[:middle])
+    right := MergeSort(arr[middle:])
+    
+    return Merge(left, right)
+}
+
+func main() {
+    arr := utils.RandArray(10)
+    fmt.Println("Initial array is:", arr)
+    fmt.Println("")
+    fmt.Println("Sorted array:    ", MergeSort(arr))
+}
+