improve grand.Intn; README updates

README.MD

@@ -66,6 +66,7 @@ func main() {
 
 # Contributors
 
+- [aloncn](https://github.com/aloncn)
 - [chenyang351](https://github.com/chenyang351)
 - [garfieldkwong](https://gitee.com/garfieldkwong)
 - [hailaz](https://gitee.com/hailaz)

README_ZH.MD

@@ -86,6 +86,7 @@ func main() {
 
 # 贡献者
 
+- [aloncn](https://github.com/aloncn)
 - [chenyang351](https://github.com/chenyang351)
 - [garfieldkwong](https://gitee.com/garfieldkwong)
 - [hailaz](https://gitee.com/hailaz)

g/util/grand/grand_intn.go

@@ -36,10 +36,15 @@ func init() {
                     i ++
                 }
                 // 充分利用缓冲区数据，随机索引递增
-                step = int(buffer[0])%10
-                if step == 0 {
-                	step = 2
+                for i := 0; i < n; i++ {
+	                step = int(buffer[0])%10
+	                if step != 0 {
+	                	break
+	                }
                 }
+	            if step == 0 {
+		            step = 2
+	            }
                 for i := 0; i < n - 4; {
                    bufferChan <- binary.BigEndian.Uint32(buffer[i : i + 4])
                    i += step