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package com.interview.misc;

import java.util.Arrays;

/**

* Date 03/26/2016

* @author Tushar Roy

*

* Given a reader which only reads 4 bytes implement a Reader which can read bytes of give size.

*

* Reference

* Read N Characters Given Read4 II

* https://leetcode.com/problems/read-n-characters-given-read4-ii-call-multiple-times/

*/

class Read4 {

int read4(char[] buff) {

buff[0] = 'a';

buff[1] = 'b';

buff[2] = 'c';

buff[3] = 'd';

return 4;

}

}

public class Read4Function extends Read4{

class Queue {

int start;

int end;

int count;

char[] data;

int size;

Queue(int size) {

data = new char[size];

this.size = size;

}

boolean isEmpty() {

return count == 0;

}

void offer(char b) {

data[start] = b;

start = (start + 1)%size;

count++;

}

char poll() {

char d = data[end];

end = (end + 1)%size;

count--;

return d;

}

}

private final Queue queue;

public Read4Function() {

queue = new Queue(4);

}

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

int r = 0;

while (!queue.isEmpty() && r < n) {

buf[r++] = queue.poll();

}

if (r == n) {

return r;

}

int index = 0;

int readSize = 0;

char[] input = null;

do {

input = new char[4];

readSize = read4(input);

index = 0;

while(r < n && index < readSize) {

buf[r++] = input[index++];

}

} while (readSize == 4 && r < n);

while (index < readSize) {

queue.offer(input[index++]);

}

return r;

}

public static void main(String args[]) {

Read4Function rf = new Read4Function();

char[] buff = new char[10];

int size = rf.read(buff, 2);

System.out.print(size);

System.out.println(Arrays.toString(buff));

size = rf.read(buff, 1);

System.out.print(size);

System.out.println(Arrays.toString(buff));

size = rf.read(buff, 1);

System.out.print(size);

System.out.println(Arrays.toString(buff));

}

}