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import java.util.ArrayList;import java.util.Stack;public class Test2 {    public static void main(String[] args) {        // ????        TreeNode root = new TreeNode(6);        TreeNode left = new TreeNode(2);        left.left = new TreeNode(0);        left.right = new TreeNode(4);        left.right.left = new TreeNode(7);        left.right.right = new TreeNode(9);        root.left = left;        TreeNode right = new TreeNode(8);        right.left = new TreeNode(3);        right.left.right = new TreeNode(5);        root.right = right;        System.out.println(lowestCommonAncestorII(root, left, right));    }    public static TreeNode lowestCommonAncestorII(TreeNode root, TreeNode p, TreeNode q) {        List
   
     pPath = findPath(root, p);        List
    
      qPath = findPath(root, q);        // ??????????null        if (pPath == null || qPath == null) {            return null;        }        // ???????????????        int minLength = Math.min(pPath.size(), qPath.size());        TreeNode common = null;        for (int i = 0; i < minLength; i++) {            if (pPath.get(i) == qPath.get(i)) {                common = pPath.get(i);            } else {                break;            }        }        return common;    }    private static List
     
       findPath(TreeNode root, TreeNode target) {        List
      
        path = new ArrayList<>();        Stack
       
         stack = new Stack<>();        stack.push(root);        while (!stack.isEmpty()) {            TreeNode node = stack.pop();            if (node == target) {                // ????????????path?                while (!stack.isEmpty()) {                    path.add(stack.pop());                }                return path;            }            if (node.left != null) {                stack.push(node.left);            }            if (node.right != null) {                stack.push(node.right);            }        }        return null;    }}
       
      
     
    
   

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• main ???????????? lowestCommonAncestorII ???????????
• lowestCommonAncestorII ?????????????????????????????
• findPath ????????DFS?????????

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