[LeetCode 157] Read N Characters Given Read4

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.

Diffculty
Easy

Similar Problems
[LeetCode ] Read N Characters Given Read4 II - Call Multiple Times Hard

Analysis