Merge pull request #29 from dwij2812/radixSort

Added Radix Sort

README.md

@@ -28,6 +28,7 @@ Algorithms
   * [heap sort](https://en.wikipedia.org/wiki/Heapsort)
   * [Shell sort](https://en.wikipedia.org/wiki/Shellsort)
   * [counting sort](https://en.wikipedia.org/wiki/Counting_sort)
+  * [radix sort](https://en.wikipedia.org/wiki/Radix_sort)
 
 #### Searching
 

sorting/radix_sort.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+)
+
+const digit = 4
+const maxbit = -1 << 31
+
+func main() {
+
+	var data = []int32{421, 15, -175, 90, -2, 214, -52, -166}
+	fmt.Println("\n--- Unsorted --- \n\n", data)
+	radixsort(data)
+	fmt.Println("\n--- Sorted ---\n\n", data, "\n")
+}
+
+func radixsort(data []int32) {
+	buf := bytes.NewBuffer(nil)
+	ds := make([][]byte, len(data))
+	for i, e := range data {
+		binary.Write(buf, binary.LittleEndian, e^maxbit)
+		b := make([]byte, digit)
+		buf.Read(b)
+		ds[i] = b
+	}
+	countingSort := make([][][]byte, 256)
+	for i := 0; i < digit; i++ {
+		for _, b := range ds {
+			countingSort[b[i]] = append(countingSort[b[i]], b)
+		}
+		j := 0
+		for k, bs := range countingSort {
+			copy(ds[j:], bs)
+			j += len(bs)
+			countingSort[k] = bs[:0]
+		}
+	}
+	var w int32
+	for i, b := range ds {
+		buf.Write(b)
+		binary.Read(buf, binary.LittleEndian, &w)
+		data[i] = w ^ maxbit
+	}
+}