黄哥所写的python文章

likepython · likepython · commit 67601170b1ba · 2016-02-16T08:27:08.000+08:00
diff --git a/python/python_recursive_prime.md b/python/python_recursive_prime.md
@@ -0,0 +1,89 @@
+#＊吧上有海外留学生问全部用递归求第N个质数，不能用循环
+
+## 习题定义了2个函数，还规定了求质数的算法，请看黄哥写的python代码和golang代码。  
+
+[点击黄哥python培训试看视频播放地址](https://github.com/pythonpeixun/article/blob/master/python_shiping.md)
+
+[黄哥python远程视频培训班](https://github.com/pythonpeixun/article/blob/master/index.md)
+
+
+
+    #coding:utf-8
+    import math
+    """
+    黄哥python北京周末培训班
+    https://github.com/pythonpeixun/article/blob/master/beijing_weekend.md
+    黄哥python远程视频培训
+    https://github.com/pythonpeixun/article/blob/master/index.md
+    咨询:qq:1465376564  黄哥python培训
+
+    """
+    def check_pr(a, b):
+        """传2个参数， a 和 b=sqrt(a),求a是不是质数"""
+        if b < 2 and a > 1:
+            return True
+        elif a % b == 0:
+            return False
+        else:
+            return check_pr(a, b-1)
+
+    def nth_prime(n):
+        """用递归替代循环求第n个质数（从2起）。"""
+        count = 0
+        def helper(i=1):
+            nonlocal count
+            if check_pr(i, int(math.sqrt(i))):
+                count += 1
+                if count == n:
+                    return i
+            return helper(i+1)
+
+        return helper
+
+    if __name__ == '__main__':
+        n = 100
+        print(nth_prime(n)())
+
+##下面是golang实现  
+
+    package main
+
+    import (
+    	"fmt"
+    	"math"
+    )
+
+    // 求质数的函数
+    func isPrime(a int, b float64) bool {
+    	if b < 2 && a > 1 {
+    		return true
+    	} else if a%int(b) == 0 {
+    		return false
+    	} else {
+    		return isPrime(a, b-1)
+    	}
+    }
+
+    // 求第N个质数
+    func nPrime(n int) int {
+    	count := 0
+    	var helper func(i int) int
+    	helper = func(i int) int {
+    		if isPrime(i, math.Sqrt(float64(i))) {
+    			count += 1
+    			if count == n {
+    				return i
+    			}
+
+    		}
+    		return helper(i + 1)
+
+    	}
+    	return helper(1)
+    }
+
+    func main() {
+    	n := 100
+    	fmt.Println(nPrime(n))
+
+    }
