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As shown in the question: Find the node with the largest value in the binary tree and return

Test data: {1,-5,3,1,2,-4,-5}

Answer: 3

Idea: Find the largest nodes of the left subtree and the right subtree from the root node, and then compare the sizes of the left subtree, right subtree, and root node to get the result. The process of obtaining the largest nodes of the left subtree and the right subtree is similar, so a recursive method can be used.

//树节点结构 public class TreeNode { TreeNode left; TreeNode right; int val; TreeNode(int val){ = val; } } public class Solution { /** * @param root 传入根节点 * @return 返回最大结果 */ public static TreeNode maxNode(TreeNode root){ //当再无子节点，返回当前节点 if (root == null) { return root; } TreeNode left = maxNode();//递归得到左子树最大值 TreeNode right = maxNode();//递归得到右子树的最大值 return max(root,max(left,right));//返回左节点，根节点,右节点的最大值 } public static TreeNode max(TreeNode a,TreeNode b) { if (a == null) { return b; } if (b == null) { return a; } if ( > ) { return a; } return b; } public static void main(String[] args) { TreeNode t1 = new TreeNode(1); TreeNode t2 = new TreeNode(-5); TreeNode t3 = new TreeNode(3); TreeNode t4 = new TreeNode(1); TreeNode t5 = new TreeNode(2); TreeNode t6 = new TreeNode(-4); TreeNode t7 = new TreeNode(-5); = t2; = t5; = t3; = t4; = t6; = t7; ((t1).val); } }