Create shortest-subarray-with-or-at-least-k-i.py

Author: kamyu104

Python/shortest-subarray-with-or-at-least-k-i.py

@@ -0,0 +1,60 @@
+# Time:  O(nlogr) = O(n * 30)
+# Space: O(logr) = O(30)
+
+# freq table, two pointers
+class Solution(object):
+    def minimumSubarrayLength(self, nums, k):
+        """
+        :type nums: List[int]
+        :type k: int
+        :rtype: int
+        """
+        def update(x, d, curr):
+            for i in xrange(len(cnt)):
+                if x < (1<<i):
+                    break
+                if not (x&(1<<i)):
+                    continue
+                if cnt[i] == 0:
+                    curr ^= 1<<i
+                cnt[i] += d
+                if cnt[i] == 0:
+                    curr ^= 1<<i
+            return curr
+
+        total = reduce(lambda x, y: x|y, nums)
+        if total < k:
+            return -1
+        cnt = [0]*total.bit_length()
+        result = len(nums)
+        left = curr = 0
+        for right in xrange(len(nums)):
+            curr = update(nums[right], +1, curr)
+            while left <= right and curr >= k:
+                result = min(result, right-left+1)
+                curr = update(nums[left], -1, curr)
+                left += 1
+        return result 
+
+
+# Time:  O(n^2)
+# Space: O(1)
+# brute force
+class Solution2(object):
+    def minimumSubarrayLength(self, nums, k):
+        """
+        :type nums: List[int]
+        :type k: int
+        :rtype: int
+        """
+        result = float("inf")
+        for left in xrange(len(nums)):
+            curr = 0
+            for right in xrange(left, len(nums)):
+                curr |= nums[right]
+                if curr < k:
+                    continue
+                result = min(result, right-left+1)
+                break
+        return result if result != float("inf") else -1
+