Give the common ancestor of all the deepest nodes of a tree

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求一颗任意树（不一定是二叉树）所有最深叶子节点（数量可以是大于等于1的任意值，取决于树的结构）的最深公共前驱节点。
例子：

如图的树中，返回的都是红色的节点。

package tree;import java.util.ArrayList;public class LowestCommonPreAncestor {    public static TreeNode find(TreeNode root) {        if (root == null || root.children.isEmpty())            return root;        return helper(root).node;    }    public static Result helper(TreeNode root) {        if (root.children.isEmpty())            return new Result(root, 1);        int size = root.children.size();        int maxDepth = Integer.MIN_VALUE;        Result r = new Result(root, maxDepth);        for (int i = 0; i < size; i++) {            Result tmp = helper(root.children.get(i));            if (tmp.maxDepth > maxDepth) {                maxDepth = tmp.maxDepth;                r.node = tmp.node;                r.maxDepth = tmp.maxDepth + 1;            }            else if (tmp.maxDepth == maxDepth) {                r.node = root;            }        }        return r;    }    public static void main(String[] args) {        TreeNode n1 = new TreeNode(1);        TreeNode n2 = new TreeNode(2);        TreeNode n3 = new TreeNode(3);        TreeNode n4 = new TreeNode(4);        TreeNode n5 = new TreeNode(5);        TreeNode n6 = new TreeNode(6);        TreeNode n7 = new TreeNode(7);        TreeNode n8 = new TreeNode(8);        TreeNode n9 = new TreeNode(9);        TreeNode n10 = new TreeNode(10);        n1.children.add(n2);        n1.children.add(n3);        n1.children.add(n4);        n2.children.add(n5);        n2.children.add(n6);        n4.children.add(n7);        n5.children.add(n8);        n5.children.add(n9);        n6.children.add(n10);        TreeNode res = find(n1);        System.out.println(res.val);    }}class TreeNode {    int val;    ArrayList<TreeNode> children;    public TreeNode(int val) {        this.val = val;        children = new ArrayList<>();    }}class Result {    TreeNode node;    int maxDepth;    public Result(TreeNode node, int maxDepth) {        this.node = node;        this.maxDepth = maxDepth;    }}

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