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.

 

这题用C 写应该简单很多。

 1 /* The read4 API is defined in the parent class Reader4.
 2       int read4(char[] buf); */
 3 
 4 public class Solution extends Reader4 {
 5     /**
 6      * @param buf Destination buffer
 7      * @param n   Maximum number of characters to read
 8      * @return    The number of characters read
 9      */
10     public int read(char[] buf, int n) {
11         int result = 0;
12         char[] tmp = new char[4];
13         while(result < n){
14             int size = super.read4(tmp);
15             for(int i = 0; i < size && result < n; i ++, result ++){
16                 buf[result] = tmp[i];
17             }
18             if(size < 4) break;
19         }
20         return result;
21     }
22 }