leetcode 238

python

Author: kyle8998

Diff for: README.md

@@ -108,6 +108,7 @@ Personal Practice Set - Doing One a Day (sometimes) in a Variety of Languages (M
 | 234| Easy       | [Palindrome Linked List](leetcode/234-Easy-Palindrome-Linked-List/problem.md)                | [Python](leetcode/234-Easy-Palindrome-Linked-List/answer.py)      |
 | 235| Easy       | [Lowest Common Ancestor of a Binary Search Tree](leetcode/235-Easy-Lowest-Common-Ancestor-Of-A-Binary-Search-Tree/problem.md) | [Python](leetcode/235-Easy-Lowest-Common-Ancestor-Of-A-Binary-Search-Tree/answer.py)|
 | 236| Medium     | [Lowest Common Ancestor of a Binary Tree](leetcode/236-Medium-Lowest-Common-Ancestor-Of-A-Binary-Tree/problem.md) | [Python](leetcode/236-Medium-Lowest-Common-Ancestor-Of-A-Binary-Tree/answer.py)|
+| 238| Medium     | [Product of Array Except Self](leetcode/238-Medium-Product-Of-Array-Except-Self/problem.md)  | [Python](leetcode/238-Medium-Product-Of-Array-Except-Self/answer.py)|
 | 258| Easy       | [Add Digits](leetcode/235-Easy-Add-Digits/problem.md)                                        | [Python](leetcode/235-Easy-Add-Digits/answer.py)                  |
 | 268| Easy       | [Missing Number](leetcode/268-Easy-Missing-Number/problem.md)                                | [Python](leetcode/268-Easy-Missing-Number/answer.py)              |
 | 283| Easy       | [Move Zeroes](leetcode/283-Easy-Move-Zeroes/problem.md)                                      | [Python](leetcode/283-Easy-Move-Zeroes/answer.py)                 |

Diff for: leetcode/238-Medium-Product-Of-Array-Except-Self/answer.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python3
+
+#-------------------------------------------------------------------------------
+# Optimal Solution O(n)
+#-------------------------------------------------------------------------------
+
+class Solution:
+    def productExceptSelf(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: List[int]
+        """
+        p = 1
+        output = []
+        
+        # We grow a product from left to right offset by 1
+        for i in range(len(nums)):
+            output.append(p)
+            p *= nums[i]
+        
+        p = 1
+        # Now we grow a product from right to left
+        # The product of the two products will be our desired result
+        for i in range(len(nums)-1, -1, -1):
+            output[i] *= p
+            p *= nums[i]
+        
+        return output
+
+#-------------------------------------------------------------------------------
+# O(n) Cheaty Division Way
+#-------------------------------------------------------------------------------   
+        
+class Solution:
+    def productExceptSelf(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: List[int]
+        """
+        output=[0]*len(nums)
+        zero = nums.count(0)
+        if zero >= 2:
+            return output
+        elif zero == 1:
+            i = 0
+            while nums[i] != 0:
+                i += 1
+            p = 1
+            for n in nums[:i] + nums[i+1:]:
+                p *= n
+            output[i] = p
+            return output
+        else:
+            p = 1
+            for n in nums:
+                p *= n   
+            for i in range(len(nums)):
+                output[i] = p//nums[i]
+            return output
+            
+#-------------------------------------------------------------------------------
+# Simple O(n^2) brute force
+#-------------------------------------------------------------------------------
+
+class Solution:
+    def productExceptSelf(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: List[int]
+        """
+        output = [1]*len(nums)
+        for i in range(len(nums)):
+            for j in range(len(nums)):
+                if i == j:
+                    continue
+                output[i] *= nums[j]
+        return output
+#-------------------------------------------------------------------------------

Diff for: leetcode/238-Medium-Product-Of-Array-Except-Self/problem.md

@@ -0,0 +1,16 @@
+# Problem 238: Product of Array Except Self
+
+#### Difficulty: Medium
+
+#### Problem
+
+Given an array nums of n integers where n > 1,  return an array output such that output[i] is equal to the product of all the elements of nums except nums[i].
+
+**Note:** Please solve it without division and in O(n).
+
+#### Example
+
+<pre>
+Input:  [1,2,3,4]
+Output: [24,12,8,6]
+</pre>

Diff for: leetcode/461-Easy-Hamming-Distance/answer.py

@@ -1,6 +1,18 @@
 #!/usr/bin/env python3
 
 #-------------------------------------------------------------------------------
+
+class Solution:
+    def hammingDistance(self, x, y):
+        """
+        :type x: int
+        :type y: int
+        :rtype: int
+        """
+        return bin(x ^ y).count('1')
+
+#-------------------------------------------------------------------------------
+
 class Solution(object):
     def hammingDistance(self, x, y):
         """
@@ -22,4 +34,3 @@ def hammingDistance(self, x, y):
 
         return count
 #-------------------------------------------------------------------------------
-# Testing