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.
一刷
题解：就是将一个很大的文件读取函数变成每4个4个的读取（读函数已写好）， 并返回总共读到的字符数目
/* 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
*/
public int read(char[] buf, int n) {
char[] buf4 = new char[4];
int offset = 0;
while(true){
int size = read4(buf4);
for(int i=0; i<size && offset<n; i++){
buf[offset++] = buf4[i];
}
if(size == 0 || offset == n) return offset;
}
}
}
二刷
同上
/* 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
*/
public int read(char[] buf, int n) {
char[] buf4 = new char[4];
int offset = 0;
while(true){
int size = read4(buf4);
for(int i=0; i<size && offset<n; i++){
buf[offset++] = buf4[i];
}
if(size == 0 || offset==n) return offset;
}
}
}
