之字打印树



import java.util.ArrayList;

import java.util.Stack;

/*

public class TreeNode {

    int val = 0;

    TreeNode left = null;

    TreeNode right = null;

 

    public TreeNode(int val) {

        this.val = val;

 

    }

 

}

*/

public class Solution {

    publicArrayList<ArrayList<Integer> > Print(TreeNode pRoot) {

        ArrayList<ArrayList<Integer> > result=newArrayList<ArrayList<Integer> >();

          if(pRoot==null)return result;

          Stack<TreeNode> s1=newStack<TreeNode>();

          Stack<TreeNode> s2=newStack<TreeNode>();

          s1.push(pRoot);

          TreeNode temp;

          ArrayList<Integer> tArrayList;

          while(!s1.empty()||!s2.empty()){

              tArrayList=newArrayList<Integer>();

              while(!s1.empty()){

                  temp=s1.pop();

                  tArrayList.add(temp.val);

                  if(temp.left!=null)

                      s2.push(temp.left);

                  if(temp.right!=null)

                      s2.push(temp.right);

              }

              if(!tArrayList.isEmpty()){

                  result.add(tArrayList);

              }

              tArrayList=newArrayList<Integer>();

              while(!s2.empty()){

                  temp=s2.pop();

                  tArrayList.add(temp.val);

                  if(temp.right!=null)

                      s1.push(temp.right);

                  if(temp.left!=null)

                      s1.push(temp.left);

              }

              if(!tArrayList.isEmpty()){

                  result.add(tArrayList);

              }

          }

        returnresult;

    }

 

}

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