LeetCode 237. Delete Node in a Linked List

237. Delete Node in a Linked List
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.

分析:因为删除结点本来的步骤是找到当前结点的前一个结点,然后修改前一个结点的 next 指针指向。现在只知道当前要删除的结点,而不知道要删除结点的前一个结点,所以可以通过修改当前要删除结点的值,然后将当前结点指针指向 next 的 next (也就是变成了把后一个结点的值赋给当前结点,然后删除要删除结点的下一个结点),达到删除结点的目的~

 

LeetCode 226. Invert Binary Tree

Invert a binary tree.

4
/ \
2 7
/ \ / \
1 3 6 9
to
4
/ \
7 2
/ \ / \
9 6 3 1
Trivia:
This problem was inspired by this original tweet by Max Howell:
Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.

 

LeetCode 111. Minimum Depth of Binary Tree

Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

LeetCode 104. Maximum Depth of Binary Tree

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.