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.
/* The read4 API is defined in the parent class Reader4.
int read4(char[] buf); */ public class Solution extends Reader4 {
/**
* @param buf Destination buffer
* @param n Maximum number of characters to read
* @return The number of characters read
*/
private char[] tmp = new char[4];
private int tmpPoint; //indicate which position we should start reading
private int tmpContain;//indicate how many char in the tmp buff
public int read(char[] buf, int n) {
int cur = 0;
while(cur < n){
if(tmpPoint == 0){
tmpContain = read4(tmp);
}
if(tmpContain == 0){
return cur;
}
while(cur < n && tmpPoint < tmpContain){
buf[cur ++] = tmp[tmpPoint ++];
}
tmpPoint = tmpPoint % tmpContain;
}
return cur;
}
}