import java.util.*; //public class TreeNode { // int val = 0; // TreeNode left = null; // TreeNode right = null; // public TreeNode(int val) { // this.val = val; // } //} // public class Tree { public static void main(String[] args) { Tree tree = new Tree(); TreeNode root = new TreeNode(5); root.left = new TreeNode(0); root.left.left = new TreeNode(1); root.left.right = new TreeNode(9); root.left.right.left = new TreeNode(10); root.right = new TreeNode(11); root.right.right = new TreeNode(7); System.out.println(tree.getDis(root)); } public int getDis(TreeNode root) { // write code here if(root == null) return 0; TreeNode[] nodes= new TreeNode[2]; nodes[0]=nodes[1]=root; getNodes(root, nodes); List pathMin = new ArrayList<>(); List pathMax = new ArrayList<>(); getPath(root, nodes[0], pathMin); getPath(root, nodes[1], pathMax); int i = 0; while(i nodes[1].val) nodes[1] = root; getNodes(root.left, nodes); getNodes(root.right, nodes); } private boolean getPath(TreeNode root, TreeNode cur, List path) { if(root == null) return false; path.add(root); if(root == cur) return true; if(getPath(root.left, cur, path)) return true; if(getPath(root.right, cur, path)) return true; path.remove(path.size()-1); return false; } }