打满鸡血来刷题

Given a positive integer, return its corresponding column title as appear in an Excel sheet.

For example:

1
2
3
4
5
6
7

1 -> A
2 -> B
3 -> C
...
26 -> Z
27 -> AA
28 -> AB

Compare two version numbers version1 and version2.
If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0.

Write a program to find the node at which the intersection of two singly linked lists begins.

For example, the following two linked lists:

Given a binary tree, return the preorder traversal of its nodes’ values.

For example:
Given binary tree {1,#,2,3},

Given a linked list, determine if it has a cycle in it.

Follow up:
Can you solve it without using extra space?

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

For example,
"A man, a plan, a canal: Panama" is a palindrome.
"race a car" is not a palindrome.

Given an index k, return the kth row of the Pascal’s triangle.

For example, given k = 3,
Return [1,3,3,1].

Given numRows, generate the first numRows of Pascal’s triangle.

For example, given numRows = 5,
Return

1
2
3
4
5
6
7

[
     [1],
    [1,1],
   [1,2,1],
  [1,3,3,1],
 [1,4,6,4,1]
]

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

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.