翻转二叉树
解法一:递归
import java.util.LinkedList;
import java.util.Queue;
public class LeetCode_226 {
public static TreeNode invertTree(TreeNode root) {
if (root == null || (root.left == null && root.right == null)) {
return root;
}
TreeNode temp = root.right;
root.right = invertTree(root.left);
root.left = invertTree(temp);
return root;
}
public static void main(String[] args) {
TreeNode root = new TreeNode(4);
root.left = new TreeNode(2);
root.right = new TreeNode(7);
root.left.left = new TreeNode(1);
root.left.right = new TreeNode(3);
root.right.left = new TreeNode(6);
root.right.right = new TreeNode(9);
invertTree(root);
Queue<TreeNode> nodes = new LinkedList<>();
nodes.add(root);
while (nodes.size() > 0) {
TreeNode cur = nodes.poll();
System.out.print(cur.val + " ");
if (cur.left != null) {
nodes.add(cur.left);
}
if (cur.right != null) {
nodes.add(cur.right);
}
}
for (TreeNode node : nodes) {
System.out.print(node.val + " ");
}
}
}