Create generate-binary-strings-without-adjacent-zeros.py

Author: kamyu104

Python/generate-binary-strings-without-adjacent-zeros.py

@@ -0,0 +1,45 @@
+# Time:  O(n * 2^n)
+# Space: O(n)
+
+# backtracking
+class Solution(object):
+    def validStrings(self, n):
+        """
+        :type n: int
+        :rtype: List[str]
+        """
+        def backtracking(i):
+            if i == n:
+                result.append("".join(curr))
+                return
+            if not curr or curr[-1] == '1':
+                curr.append('0')
+                backtracking(i+1)
+                curr.pop()
+            curr.append('1')
+            backtracking(i+1)
+            curr.pop()
+
+        result, curr = [], []
+        backtracking(0)
+        return result
+
+
+# Time:  O(n * 2^n)
+# Space: O(n * 2^n)
+# bfs
+class Solution2(object):
+    def validStrings(self, n):
+        """
+        :type n: int
+        :rtype: List[str]
+        """
+        q = [[]]
+        for _ in xrange(n):
+            new_q = []
+            for x in q:
+                if not x or x[-1] == '1':
+                    new_q.append(x+['0'])
+                new_q.append(x+['1'])
+            q = new_q
+        return ["".join(x) for x in q]