Create sequential-digits.py

Author: kamyu104

Python/sequential-digits.py

@@ -0,0 +1,24 @@
+# Time:  O((8 + 1) * 8 / 2) = O(1)
+# Space: O(8) = O(1)
+
+import collections
+
+
+class Solution(object):
+    def sequentialDigits(self, low, high):
+        """
+        :type low: int
+        :type high: int
+        :rtype: List[int]
+        """
+        result = []
+        q = collections.deque(range(1, 9))
+        while q:
+            num = q.popleft()
+            if num > high:
+                continue
+            if low <= num:
+                result.append(num)
+            if num%10+1 < 10:
+                q.append(num*10+num%10+1)
+        return result