InvertBinaryTree
InvertBinaryTree.java 源码
package algorithm.recursion;
import java.util.LinkedList;
import java.util.Queue;
/**
* @author roseduan
* @time 2020/9/22 10:04 下午
* @description 翻转二叉树
*/
public class InvertBinaryTree {
/**
* 递归
*/
public TreeNode invertTree(TreeNode root) {
if (root == null) {
return null;
}
TreeNode left = invertTree(root.left);
root.left = invertTree(root.right);
root.right = left;
return root;
}
/**
* 迭代，类似于广度优先搜索的方法
*/
public TreeNode invertTree2(TreeNode root) {
if (root == null) {
return null;
}
Queue<TreeNode> queue = new LinkedList<>();
queue.add(root);
while (!queue.isEmpty()) {
TreeNode node = queue.poll();
TreeNode temp = node.left;
node.left = node.right;
node.right = temp;
if (node.left != null) {
queue.add(node.left);
}
if (node.right != null) {
queue.add(node.right);
}
}
return root;
}
public class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode() {}
TreeNode(int val) { this.val = val; }
TreeNode(int val, TreeNode left, TreeNode right) {
this.val = val;
this.left = left;
this.right = right;
}
}
}
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