update lesson16

Author: jincheng9

readme.md

@@ -15,4 +15,5 @@
 * [lesson13: 切片Slice](./workspace/lesson13)
 * [lesson14: range迭代](./workspace/lesson14)
 * [lesson15: map集合](./workspace/lesson15)
+* [lesson16: 递归函数](./workspace/lesson16)
 

workspace/lesson16/readme.md

@@ -0,0 +1,26 @@
+# 递归函数
+
+* 和C++的递归一样
+
+  ```go
+  package main
+  
+  import "fmt"
+  
+  
+  // 计算n的阶乘
+  func factorial(n int) int {
+      if n == 0 || n == 1 {
+          return 1
+      } else {
+          return n * factorial(n-1)
+      }
+  }
+  
+  func main() {
+      sum := factorial(5)
+      fmt.Println("5!=", sum)
+  }
+  ```
+
+  

workspace/lesson16/recursion.go

@@ -0,0 +1,18 @@
+package main
+
+import "fmt"
+
+
+// 计算n的阶乘
+func factorial(n int) int {
+    if n == 0 || n == 1 {
+        return 1
+    } else {
+        return n * factorial(n-1)
+    }
+}
+
+func main() {
+    sum := factorial(5)
+    fmt.Println("5!=", sum)
+}