leetcode 收费的3道新题目

看到有同学在地里发帖说看不了。 我这里发出来。
话说45块确实有点贵。 我是当时15块买的。 过2天就涨到了45块了。  10道题，一道4块。。

发现看不到图。发文字好了
Given a binary tree where all the right nodes are either leaf nodes with a sibling (a left node that shares the same parent node) or empty, flip it upside down and turn it into a tree where the original right nodes turned into left leaf nodes. Return the new root.
For example:
Given a binary tree {1,2,3,4,5},

    1
   / \
  2   3
/ \
4   5

return the root of the binary tree [4,5,2,#,#,3,1].

   4
  / \
5   2
    / \
   3   1  

confused what "{1,#,2,3}" means? > read more on how binary tree is serialized on OJ.




Read N Characters Given Read4
Total Accepted: 300 Total Submissions: 1516

The API: int read4(char *buf) reads 4 characters at a time from a file.

The return value is the actual number of characters read. For example, it returns 3 if there is only 3 characters left in the file.

By using the read4 API, implement the function int read(char *buf, int n) that reads n characters from the file.

Note:
The read function will only be called once for each test case.





Read N Characters Given Read4 II - Call multiple times
Total Accepted: 122 Total Submissions: 1026

The API: int read4(char *buf) reads 4 characters at a time from a file.

The return value is the actual number of characters read. For example, it returns 3 if there is only 3 characters left in the file.

By using the read4 API, implement the function int read(char *buf, int n) that reads n characters from the file.

Note:
The read function may be called multiple times.





Longest Substring with At Most Two Distinct Characters
Total Accepted: 27 Total Submissions: 82

Given a string, find the length of the longest substring T that contains at most 2 distinct characters.

For example, Given s = “eceba”,

T is "ece" which its length is 3.

LZ土豪快和我做朋友！

楼主好人！！！

thanks, lz. hao ren yi sheng ping an a

谢谢LZ 分享！

感谢分享，生命不息，刷题不止

祝lz offer多多！

楼主这个好！谢啦！