[20180411] medium problems

Author: iamminji

README.md

@@ -105,6 +105,7 @@
 | [0695](https://leetcode.com/problems/max-area-of-island/description/)                        | Max Area of Island                        | easy       | python         |           |
 | [0696](https://leetcode.com/problems/count-binary-substrings/)                        | Count Binary Substrings                        | easy       | [python](🙂easy/0696.Count-Binary-Substrings/count_binary_substrings.py)         |           |
 | [0700](https://leetcode.com/problems/search-in-a-binary-search-tree/)                                    | Search in a Binary Search Tree                        | easy       | [python](🙂easy/0700.Search-in-a-Binary-Search-Tree/search_in_a_binary_search_tree.py)         |           |
+| [0701](https://leetcode.com/problems/insert-into-a-binary-search-tree/)                                    | Insert into a Binary Search Tree                        | medium       | [python](🤔medium/0701.Insert-into-a-Binary-Search-Tree/insert_into_a_binary_search_tree.py)         |           |
 | [0707](https://leetcode.com/problems/design-linked-list/)                                    | Design Linked List                        | easy       | golang         |           |
 | [0709](https://leetcode.com/problems/to-lower-case/description/)                             | To Lower Case                             | easy       | golang         |           |
 | [0728](https://leetcode.com/problems/self-dividing-numbers/description/)                     | Self Dividing Numbers                     | easy       | python         |           |

🤔medium/0701.Insert-into-a-Binary-Search-Tree/insert_into_a_binary_search_tree.py

@@ -0,0 +1,45 @@
+# 701. Insert into a Binary Search Tree
+# https://leetcode.com/problems/insert-into-a-binary-search-tree/
+
+
+# Definition for a binary tree node.
+class TreeNode(object):
+    def __init__(self, x):
+        self.val = x
+        self.left = None
+        self.right = None
+
+
+class Solution(object):
+    # val 이라는 값이 들어올 때 TreeNode 에 위치시키는 문제다.
+    # 이 때 Tree는 BinaryTree다.
+    def helper(self, node, val):
+
+        # leaf node 에 위치시키도록 했다.
+        # 바이너리 트리이기 때문에 값 비교하면서 가장 하단 까지 내려가면 된다.
+        if node is None:
+            return
+
+        if node.val < val:
+            if node.right is not None:
+                self.helper(node.right, val)
+            else:
+                node.right = TreeNode(val)
+                return
+        else:
+            if node.left is not None:
+                self.helper(node.left, val)
+            else:
+                node.left = TreeNode(val)
+                return
+
+        return
+
+    def insertIntoBST(self, root, val):
+        """
+        :type root: TreeNode
+        :type val: int
+        :rtype: TreeNode
+        """
+        self.helper(root, val)
+        return root