Create check-if-a-string-contains-all-binary-codes-of-size-k.py

Author: kamyu104

Python/check-if-a-string-contains-all-binary-codes-of-size-k.py

@@ -0,0 +1,33 @@
+# Time:  O(n * k)
+# Space: O(k * 2^k)
+
+class Solution(object):
+    def hasAllCodes(self, s, k):
+        """
+        :type s: str
+        :type k: int
+        :rtype: bool
+        """
+        return 2**k <= len(s) and len({s[i:i+k] for i in xrange(len(s)-k+1)}) == 2**k
+    
+
+# Time:  O(n * k)
+# Space: O(2^k)
+class Solution2(object):
+    def hasAllCodes(self, s, k):
+        """
+        :type s: str
+        :type k: int
+        :rtype: bool
+        """
+        lookup = set()
+        base = 2**k
+        if base > len(s):
+            return False
+        num = 0
+        for i in xrange(len(s)):
+            num = (num << 1) + (s[i] == '1')
+            if i >= k-1:
+                lookup.add(num)
+                num -= (s[i-k+1] == '1') * (base//2)
+        return len(lookup) == base