Update adjacentElementProduct.py

Author: Amogh Singhal

adjacentElementProduct.py

@@ -1,7 +1,40 @@
-#Given an array of integers,
-#find the pair of adjacent elements 
-#that has the largest product and 
-#return that product.
+# Given an array of integers, find the pair of adjacent elements 
+# that has the largest product and return that product.
+
+# Approach 1: (Brute Force) - Check all the pairs in the list and then return the maximum pair
+# Time Complexity: O(N^2)
+
+def adjacentElementProductBF(inputArray):
+	largestProduct = -999999
+	
+	# for sanity check, assert if array contains at least 2 elements
+	if len(inputArray) < 2:
+		print("No pairs exists")
+		return -1
+	
+	for i in range(0, len(inputArray)):
+		for j in range(i+1, len(inputArray)):
+			currentProduct = inputArray[i]*inputArray[j]
+			
+			if currentProduct > largestProduct:
+				largestProduct = currentProduct
+	
+	return largestProduct
+
+# Approach 2: (Sort & Pick Last Pair) - Sort the list and then pick the last two numbers
+# Caveat: All elements must be positive
+# Time Complexity: O(Nlog(N))
+
+def adjacentElementsProductSort(inputArray):
+	size = len(inputArray)
+	
+	if size < 2:
+		print("No Pairs exist")
+		return -1
+	
+	sortedArray = sorted(inputArray)
+	return sortedArray[-1] * sortedArray[-2] 
+
 
 def adjacentElementsProduct(inputArray):	
 
@@ -24,11 +57,3 @@ def adjacentElementsProduct(inputArray):
 
 #Alternate solution
 #return max([inputArray[i]*inputArray[i+1] for i in range(0, int(len(inputArray)-1))])
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