Update README.md

README.md

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-# BFS-3
+# BFS-3
+
+## Problem1 Remove Invalid Parentheses(https://leetcode.com/problems/remove-invalid-parentheses/)
+
+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: [""]
+
+## Problem2 Clone graph (https://leetcode.com/problems/clone-graph/)
+
+Given a reference of a node in a connected undirected graph, return a deep copy (clone) of the graph. Each node in the graph contains a val (int) and a list (List[Node]) of its neighbors.
+
+
+
+Example:
+
+Input:
+{"$id":"1","neighbors":[{"$id":"2","neighbors":[{"$ref":"1"},{"$id":"3","neighbors":[{"$ref":"2"},{"$id":"4","neighbors":[{"$ref":"3"},{"$ref":"1"}],"val":4}],"val":3}],"val":2},{"$ref":"4"}],"val":1}
+
+Explanation:
+
+Node 1's value is 1, and it has two neighbors: Node 2 and 4.
+
+Node 2's value is 2, and it has two neighbors: Node 1 and 3.
+
+Node 3's value is 3, and it has two neighbors: Node 2 and 4.
+
+Node 4's value is 4, and it has two neighbors: Node 1 and 3.
+
+
+Note:
+
+The number of nodes will be between 1 and 100.
+
+The undirected graph is a simple graph, which means no repeated edges and no self-loops in the graph.
+
+Since the graph is undirected, if node p has node q as neighbor, then node q must have node p as neighbor too.
+
+You must return the copy of the given node as a reference to the cloned graph.