ch22test

// Jimimport java.io.File;public class stuff{  public static boolean isPower2(int n)  {    return n >= 1 && (n == 2 || isPower2(n / 2));  }  public ListNode reverse(ListNode head)  {    if(head == null)      return null;    return new ListNode(head.getValue(), reverse(head.getNext()));  }  private boolean isWord(String s)  {    return s.length() > 0 & Character.isLetter(s.charAt(0)) &&            (s.length() == 1 || isWord(s.substring(0)));  }  public boolean isPhrase(String s)  {    String[] words = s.split(" ");    return isWord(words[0]) &&            (words[0].length() == s.length() ||            isPhrase(s.substring(words[0].length()+1)));  }  public long getTotalSize(File x)  {    if(!x.isDirectory())      return x.length();    else    {      long size = 0;      File[] files = x.listFiles();      for(File thisfile:files)      {        size += getTotalSize(thisfile);      }      return size;    }  }  public int getSum(int[][] grid, int r, int c)  {    int sum = 0;    if(r >= 0 && c >= 0 && r < grid.length &&        c < grid[0].length && grid[r][c] > 0)    {      grid[r][c] = 0;      sum += getSum(grid, r-1, c);      sum += getSum(grid, r+1, c);      sum += getSum(grid, r, c-1);      sum += getSum(grid, r, c+1);    }    return sum;  }}