Delete Node in a Linked List/ Product of Array Except Self

Author: gavinfish

237 Delete Node in a Linked List.py

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+'''
+Write a function to delete a node (except the tail) in a singly linked list,
+given only access to that node.
+
+Supposed the linked list is 1 -> 2 -> 3 -> 4 and you are given the third node
+with value 3, the linked list should become 1 -> 2 -> 4 after calling your
+function.
+'''
+
+# Definition for singly-linked list.
+class ListNode(object):
+    def __init__(self, x):
+        self.val = x
+        self.next = None
+
+class Solution(object):
+    def deleteNode(self, node):
+        """
+        :type node: ListNode
+        :rtype: void Do not return anything, modify node in-place instead.
+        """
+        node.val = node.next.val
+        node.next = node.next.next
+                
+            
+if __name__=="__main__":
+    n1 = ListNode(1)
+    n2 = ListNode(2)
+    n3 = ListNode(3)
+    n4 = ListNode(4)
+    n1.next = n2
+    n2.next = n3
+    n3.next = n4
+    Solution().deleteNode(n3)
+    assert n2.next.val == 4

238 Product of Array Except Self.py

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+'''
+Given an array of n integers where n > 1, nums, return an array output such that output[i] is equal to the product of all the elements of nums except nums[i].
+
+Solve it without division and in O(n).
+
+For example, given [1,2,3,4], return [24,12,8,6].
+
+Follow up:
+Could you solve it with constant space complexity? (Note: The output array does not count as extra space for the purpose of space complexity analysis.)
+'''
+
+class Solution(object):
+    def productExceptSelf(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: List[int]
+        """
+        n = len(nums)
+        result = [1] * n
+        for i in range(1, n):
+            result[i] = result[i - 1] * nums[i - 1]
+        temp = 1
+        for i in range(n - 1, -1, -1):
+            result[i] *= temp
+            temp *= nums[i]
+        return result
+
+
+if __name__ == "__main__":
+    assert Solution().productExceptSelf([1, 2, 3, 4]) == [24, 12, 8, 6]