From 8ed6b29fe0c005e3da7fcb41ebc5758af17f5c50 Mon Sep 17 00:00:00 2001
From: Dong Liang <dong.liang@finzsoft.com>
Date: Thu, 13 Jul 2017 16:38:18 +1200
Subject: [PATCH] Add Golang Version

---
 Go/ShortURL.go | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 Go/ShortURL.go

diff --git a/Go/ShortURL.go b/Go/ShortURL.go
new file mode 100644
index 0000000..e4074e4
--- /dev/null
+++ b/Go/ShortURL.go
@@ -0,0 +1,46 @@
+/*
+ * ShortURL (https://github.com/delight-im/ShortURL)
+ * Copyright (c) delight.im (https://www.delight.im/)
+ * Licensed under the MIT License (https://opensource.org/licenses/MIT)
+ */
+
+/**
+ * shorturl: Bijective conversion between natural numbers (IDs) and short strings
+ *
+ * shorturl.Encode() takes an ID and turns it into a short string
+ * shorturl.Decode() takes a short string and turns it into an ID
+ *
+ * Features:
+ * + large alphabet (51 chars) and thus very short resulting strings
+ * + proof against offensive words (removed 'a', 'e', 'i', 'o' and 'u')
+ * + unambiguous (removed 'I', 'l', '1', 'O' and '0')
+ *
+ * Example output:
+ * 123456789 <=> pgK8p
+ */
+
+package shorturl
+
+import (
+	"strings"
+)
+
+const Alphabet string = "23456789bcdfghjkmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ-_"
+const Base int = len(Alphabet)
+
+func Encode(num int) string {
+	bytes := []byte{}
+	for num > 0 {
+		bytes = append([]byte{Alphabet[num%Base]}, bytes...)
+		num = num / Base
+	}
+	return string(bytes)
+}
+
+func Decode(str string) int {
+	num := 0
+	for i := 0; i < len(str); i++ {
+		num = num*Base + strings.Index(Alphabet, string(str[i]))
+	}
+	return num
+}