Read N Characters Given Read4 II - Call multiple times

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.

 

 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     private char[] tmp = new char[4];
11     private int tmpPoint; //indicate which position we should start reading
12     private int tmpContain;//indicate how many char in the tmp buff
13     public int read(char[] buf, int n) {
14         int cur = 0;
15         while(cur < n){
16             if(tmpPoint == 0){
17                 tmpContain = read4(tmp);
18             }
19             if(tmpContain == 0){
20                 return cur;
21             }
22             while(cur < n && tmpPoint < tmpContain){
23                 buf[cur ++] = tmp[tmpPoint ++];
24             }
25             tmpPoint = tmpPoint % tmpContain;
26         }
27         return cur;
28     }
29 }

 

posted on 2015-04-17 07:11  Step-BY-Step  阅读(175)  评论(0)  编辑  收藏  举报

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