Solution of Remove Invalid Parentheses and Binary Tree Paths

200-300q/257.py

@@ -0,0 +1,50 @@
+'''
+	Given a binary tree, return all root-to-leaf paths.
+
+	Note: A leaf is a node with no children.
+
+	Example:
+
+	Input:
+
+	   1
+	 /   \
+	2     3
+	 \
+	  5
+
+	Output: ["1->2->5", "1->3"]
+
+	Explanation: All root-to-leaf paths are: 1->2->5, 1->3
+'''
+
+# 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):
+    def binaryTreePaths(self, root):
+        """
+        :type root: TreeNode
+        :rtype: List[str]
+        """
+        if not root:
+            return []
+
+        paths = []
+        def dfs(root, curr):
+            if root.left is None and root.right is None:
+                paths.append(curr + str(root.val))
+                return
+
+            if root.left:
+                dfs(root.left, curr + str(root.val) + '->')
+            if root.right:
+                dfs(root.right, curr + str(root.val) + '->')
+
+        curr = ""
+        dfs(root, curr)
+        return paths

300-400q/301.py

@@ -0,0 +1,63 @@
+'''
+	Remove the minimum number of invalid parentheses in order to make the input string valid. Return all possible results.
+
+	Note: The input string may contain letters other than the parentheses ( and ).
+
+	Example 1:
+
+	Input: "()())()"
+	Output: ["()()()", "(())()"]
+	Example 2:
+
+	Input: "(a)())()"
+	Output: ["(a)()()", "(a())()"]
+	Example 3:
+
+	Input: ")("
+	Output: [""]
+'''
+
+class Solution(object):
+    def removeInvalidParentheses(self, s):
+        """
+        :type s: str
+        :rtype: List[str]
+        """
+        if not s:
+        	return [""]
+
+        def isValid(s):
+        	count = 0
+        	for char in s:
+        		if char == '(':
+        			count += 1
+        		elif char == ')':
+        			count -= 1
+        		if count < 0:
+        			return False
+        	return (count==0)
+
+        queue, result = [s], []
+        visited = set()
+        visited.add(s)
+        level = False
+
+        while queue:
+        	new_str = queue.pop(0)
+        	if isValid(new_str):
+        		result.append(new_str)
+        		level = True
+
+        	if level:
+        		continue
+
+        	for index in range(len(new_str)):
+        		if not (new_str[index] == "(" or new_str[index] == ")"):
+        			continue
+        		partition_str = new_str[0:index] + new_str[index+1:]
+        		if partition_str not in visited:
+	        		queue.append(partition_str)
+	        		visited.add(partition_str)
+        return result
+
+

README.md

@@ -18,7 +18,7 @@ Python solution of problems from [LeetCode](https://leetcode.com/).
 |326|[Power of Three](https://leetcode.com/problems/power-of-three/) | [Python](./300-400q/326.py)|Easy|
 |322|[Coin Change](https://leetcode.com/problems/coin-change/) | [Python](./300-400q/322.py)|Medium|
 |315|[Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self/) | [Python](./300-400q/315.py)|Hard|
-
+|301|[Remove Invalid Parentheses](https://leetcode.com/problems/remove-invalid-parentheses)|[Python](./300-400q/301.py)|Hard|
 
 ##### [Problems 200-300q](./200-300q/)
 | # | Title | Solution | Difficulty |
@@ -32,6 +32,7 @@ Python solution of problems from [LeetCode](https://leetcode.com/).
 |283|[Move Zeros](https://leetcode.com/problems/move-zeroes)|[Python](./200-300q/283.py)|Easy|
 |279|[Perfect Squares](https://leetcode.com/problems/perfect-squares/) | [Python](./200-300q/279.py)|Medium|
 |268|[Missing Number](https://leetcode.com/problems/missing-number)|[Python](./200-300q/268.py)|Easy|
+|257|[Binary Tree Paths](https://leetcode.com/problems/binary-tree-paths)[Python](./200-300q/257.py)|Easy|
 |253|[Meeting Rooms II](https://leetcode.com/problems/meeting-rooms-ii) | [Python](./200-300q/253.py)|Medium|
 |240|[Search a 2D Matrix II](https://leetcode.com/problems/search-a-2d-matrix-ii/)|[Python](./200-300q/240.py)|Medium|
 |239|[Sliding Window Maximum](https://leetcode.com/problems/sliding-window-maximum/)| [Python](./200-300q/239.py)|Hard|