632. 二叉树的最大节点

在二叉树中寻找值最大的节点并返回。
样例
给出如下一棵二叉树：

     1
   /   \
 -5     2
 / \   /  \
0   3 -4  -5

Java 代码

import LintClass.TreeNode;

/**
 * Definition of TreeNode:
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left, right;
 *     public TreeNode(int val) {
 *         this.val = val;
 *         this.left = this.right = null;
 *     }
 * }
 */
public class MaxNode_632 {

    TreeNode max = new TreeNode(Integer.MIN_VALUE);
    /*
     * @param root: the root of tree
     * @return: the max node
     */
    public TreeNode maxNode(TreeNode root) {
        // write your code here
        if(root == null ) {
            return root;
        }
        max = max.val > root.val ? max: root;
        maxNode(root.left);
        maxNode(root.right);
        return max;
    }
    
    public static void main(String[] arg) {
        TreeNode tree = new TreeNode(1);
        TreeNode tree_1_left = new TreeNode(-5);
        TreeNode tree_1_right = new TreeNode(2);
        TreeNode tree_2_left_left = new TreeNode(0);
        TreeNode tree_2_left_right = new TreeNode(3);
        TreeNode tree_2_right_left = new TreeNode(-4);
        TreeNode  tree_2_right_right = new TreeNode(-5);
        tree.left = tree_1_left;
        tree.right = tree_1_right;
        tree.left.left = tree_2_left_left;
        tree.left.right = tree_2_left_right;
        tree.right.left = tree_2_right_left;
        tree.right.right = tree_2_right_right;
        
        MaxNode_632 obj = new MaxNode_632();
        System.out.print(obj.maxNode(tree).val);
    }
}