package leetcode;

import java.util.ArrayList;

import java.util.Arrays;

/*

* 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.

*/

public class ReadNCharacter2 {

char a = 'a';

ArrayList<Character> buffer = new ArrayList<Character>();

public char[] bufferChar = new char[4];

public int read(char[] buf, int n){

int counter = 0;

if(buffer.size() > 0){

while(counter<n && buffer.size()>0){

buf[counter] = buffer.remove(0);

counter++;

}

if(buffer.size() > 0)

return n;

}

// System.out.println(counter);

while(counter < n){

char[] temp = new char[4];

int r = read4(temp);

int i;

for(i=0;i<r && counter<n;i++){

buf[counter++] = temp[i];

}

while(i < r){

buffer.add(temp[i++]);

}

if(r < 4)

break;

}

return counter;

}

private int read4(char[] buf){

for(int i=0;i<4;i++){

buf[i] = this.a++;

}

return 4;

}

public static void main(String[] args) {

ReadNCharacter2 rc = new ReadNCharacter2();

int n = 5;

char[] buf = new char[n];

rc.read(buf, n);

System.out.println(buf);

System.out.println(Arrays.toString(rc.bufferChar));

rc.read(buf, n);

System.out.println(buf);

System.out.println(Arrays.toString(rc.bufferChar));

rc.read(buf, n);

System.out.println(buf);

System.out.println(Arrays.toString(rc.bufferChar));

rc.read(buf, n);

System.out.println(buf);

}

}