数据结构与算法-第12章二叉树和其他树-001遍历

以下例子的树是存在数组中

1.中序遍历

package chapter12Tree;

public class ArrayBinaryTreeWithInorder
{
   // data members
   static Object [] a;   // array that contains the tree
   static int last;      // position of last element in array a

   /** visit method that prints the element in a[i] */ 
   public static void visit(int i)
      {System.out.print(a[i] + " ");}


   /** inorder traversal */
   public static void inOrder(Object [] theArray, int theLast)
   {
      // set static data members
      a = theArray;
      last = theLast;

      // start the recursive traversal method at the root
      theInOrder(1);
   }

   /** actual method to do the inorder traversal */
   static void theInOrder(int i)
   {// traverse subtree rooted at a[i]
      if (i <= last && a[i] != null)
      {// root exists
         theInOrder(2 * i);         // do left subtree
         visit(i);                  // visit tree root
         theInOrder(2 * i + 1);     // do right subtree
      }
   }
   
   public static void main(String[] args) {
       Object [] a = {0,1,2,3,4,5}; //第一个位置没用
       inOrder(a, a.length-1); //输出4 2 5 1 3 
   }
}

2.平层遍历

package chapter12Tree;

//Since the elements are stored in the array by levels, 
//a level order traversal may be done by examining the array 
//from left to right. The code is given below. 
public class ArrayBinaryTreeWithLevelOrder
{
   static Object [] a;   // array that contains the tree

   /** visit method that prints the element in a[i] */ 
   public static void visit(int i)
      {System.out.print(a[i] + " ");}

   /** level order traversal */
   public static void levelOrder(Object [] theArray, int last)
   {
      a = theArray;
      for (int i = 1; i <= last; i++)
         if (a[i] != null)
            visit(i);  
   }
   
   public static void main(String[] args) {
       Object [] a = {0,1,2,3,4,5}; //第一个位置没用
       levelOrder(a, a.length-1); //输出1 2 3 4 5  
   }
}