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PrintTreeZ.java
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80 lines (71 loc) · 2.74 KB
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package Chap4;
import java.util.ArrayList;
import java.util.LinkedList;
/**
* 按照Z字形打印二叉树，即先打印根结点，然后从右往左打印第二层，从左往右打印第三层...以此类推
*/
public class PrintTreeZ {
private class TreeNode {
int val = 0;
TreeNode left = null;
TreeNode right = null;
public TreeNode(int val) {
this.val = val;
}
}
public void printTreeZ(TreeNode root) {
if (root == null) return;
LinkedList<TreeNode> stackOdd = new LinkedList<>();
LinkedList<TreeNode> stackEven = new LinkedList<>();
stackOdd.push(root);
// 只要还有一个栈不为空就继续
while (!stackOdd.isEmpty() || !stackEven.isEmpty()) {
if (!stackOdd.isEmpty()) {
while (!stackOdd.isEmpty()) {
TreeNode node = stackOdd.pop();
System.out.println((node.val + " "));
if (node.left != null) stackEven.push(node.left);
if (node.right != null) stackEven.push(node.right);
}
} else {
while (!stackEven.isEmpty()) {
TreeNode node = stackEven.pop();
System.out.println((node.val + " "));
if (node.right != null) stackOdd.push(node.right);
if (node.left != null) stackOdd.push(node.left);
}
}
System.out.println();
}
}
public ArrayList<ArrayList<Integer>> print(TreeNode root) {
ArrayList<ArrayList<Integer>> list = new ArrayList<>();
if (root == null) {
return list;
}
LinkedList<TreeNode> stackOdd = new LinkedList<>();
LinkedList<TreeNode> stackEven = new LinkedList<>();
stackOdd.push(root);
// 只要还有一个栈不为空就继续
while (!stackOdd.isEmpty() || !stackEven.isEmpty()) {
ArrayList<Integer> layerList = new ArrayList<>();
if (!stackOdd.isEmpty()) {
while (!stackOdd.isEmpty()) {
TreeNode node = stackOdd.pop();
layerList.add(node.val);
if (node.left != null) stackEven.push(node.left);
if (node.right != null) stackEven.push(node.right);
}
} else {
while (!stackEven.isEmpty()) {
TreeNode node = stackEven.pop();
layerList.add(node.val);
if (node.right != null) stackOdd.push(node.right);
if (node.left != null) stackOdd.push(node.left);
}
}
list.add(layerList);
}
return list;
}
}