Merge pull request keon#64 from shruti19/master

program changed from ruby to python

Author: ankit167

dp/max_product_subarray.py

@@ -19,3 +19,46 @@ def max_product(nums):
         lmax = max(max(t1, t2), nums[i])
         lmin = min(min(t1, t2), nums[i])
         gmax = max(gmax, lmax)
+
+
+'''
+Another approach that would print max product and the subarray
+
+Examples:
+subarray_with_max_product([2,3,6,-1,-1,9,5])
+    #=> max_product_so_far: 45, [-1, -1, 9, 5]
+subarray_with_max_product([-2,-3,6,0,-7,-5])
+    #=> max_product_so_far: 36, [-2, -3, 6]
+subarray_with_max_product([-4,-3,-2,-1])
+    #=> max_product_so_far: 24, [-4, -3, -2, -1]
+subarray_with_max_product([-3,0,1])
+    #=> max_product_so_far: 1, [1]
+'''
+
+def subarray_with_max_product(arr):
+    ''' arr is list of positive/negative numbers '''
+    l = len(arr)
+    product_so_far = max_product_end = 1
+    max_start_i = 0
+    so_far_start_i = so_far_end_i = 0
+    all_negative_flag = True
+
+    for i in range(l):
+        max_product_end *= arr[i]
+        if arr[i] > 0: all_negative_flag = False
+
+        if max_product_end <= 0:
+            max_product_end = arr[i]
+            max_start_i = i
+
+        if product_so_far <= max_product_end:
+            product_so_far = max_product_end
+            so_far_end_i = i
+            so_far_start_i = max_start_i
+    
+    if all_negative_flag:
+        print "max_product_so_far: %s, %s" % \
+            (reduce(lambda x, y: x * y, arr), arr)
+    else:
+        print "max_product_so_far: %s, %s" % (product_so_far,\
+	       arr[so_far_start_i:so_far_end_i + 1])