two-state dp

Maximum Product Subarray.py

@@ -0,0 +1,29 @@
+"""
+Find the contiguous subarray within an array (containing at least one number) which has the largest product.
+
+Example
+For example, given the array [2,3,-2,4], the contiguous subarray [2,3] has the largest product = 6.
+"""
+__author__ = 'Daniel'
+
+
+class Solution(object):
+    def maxProduct(self, nums):
+        if not nums:
+            return 0
+
+        n = len(nums)
+        smallest = list(nums)
+        largest = list(nums)
+        maxa = nums[0]
+        for i in xrange(1, n):
+            v = nums[i]
+            smallest[i] = min(v, smallest[i-1]*v, largest[i-1]*v)
+            largest[i] = max(v, smallest[i-1]*v, largest[i-1]*v)
+            maxa = max(maxa, largest[i])
+
+        return maxa
+
+
+if __name__ == "__main__":
+    assert Solution().maxProduct([2, 3, -2, 4]) == 6