Formatted question description: https://leetcode.ca/all/157.html
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.
Read every 4, and then judge the results,
- If it is 0, it means that the buf has been read at this time, and the loop is jumped out, and the smaller value of res and n is directly returned.
- Otherwise, keep reading until n characters are read, the loop ends, and finally the smaller value of res and n is returned