Merge pull request #171 from mikechengwei/master

修改: fd-growth 算法文档

Author: wangyangting

docs/12.使用FP-growth算法来高效发现频繁项集.md

@@ -26,8 +26,8 @@ class treeNode:
         self.count = numOccur     # 节点出现次数
         self.nodeLink = None      # 不同项集的相同项通过nodeLink连接在一起
         # needs to be updated
-        self.parent = parentNode  # 节点的父节点
-        self.children = {}        # 存储儿子节点
+        self.parent = parentNode  # 指向父节点
+        self.children = {}        # 存储叶子节点
 ```   
          
 ## FP-growth 原理