Read N Characters Given Read4 II - Call multiple times

同I，此题还是最重要的还是得能准确理解题意，然后对着I的解法稍作修改，做的时候先把I写一遍，再改成II，这是最好的。

/* The read4 API is defined in the parent class Reader4.
      int read4(char[] buf); */

public class Solution extends Reader4 {
    Queue<Character> queue = new LinkedList<>();
    /**
     * @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) {
        if (n == 0) {
            return 0;
        }
        char[] temp = new char[4];
        boolean eof = false;
        int readCount = 0;
        
        /////////////////
        while (!queue.isEmpty() && readCount < n) {
            buf[readCount++] = queue.poll();
        }
        /////////////////
        
        while (!eof && readCount < n) {
            int count = read4(temp);
            if (count < 4) {
                eof = true;
            }
            /////////////////
            int finalCount = Math.min(count, n - readCount);
            int i = 0;
            /////////////////
            for (; i < finalCount; i++) {
                buf[readCount++] = temp[i];
            }
            /////////////////
            if (finalCount < count) {
                for (; i < count; i++) {
                    queue.offer(temp[i]);
                }
            }
            /////////////////
        }
        return readCount;
    }
}