Longest increasing path in n-ary tree

https://gist.github.com/gcrfelix/4ebb4b8c8b8c894d38a7
多叉树，每个节点是一个整数，求树中最长递增路径比如5,6,7,8,9

public class Solution {

  int longest = 0;
 
  public int findLongestPath(TreeNode root) {
    if(root == null) {
      return 0;
    }
    if(root.children == null || root.children.size() == 0) {
      return 1;
    }
    longest = 1;
    for(int i=0; i<root.children.size(); i++) {
      findLongestPath(root.children.get(i), root.val, 1);
    }
    return longest;
  }
 
  public void findLongestPath(TreeNode root, int pre, int len) {
    if(root == null) {
      longest = Math.max(len, longest);
      return;
    }
    if(root.children == null || root.children.size() == 0) {
      longest = Math.max(len+1, longest);
      return;
    }
    if(root.val > pre) {
      for(int i=0; i<root.children.size(); i++) {
        findLongestPath(root.children.get(i), root.val, len+1);
      }
    } else {
      for(int i=0; i<root.children.size(); i++) {
        findLongestPath(root.children.get(i), root.val, 1);
      }
    }
  }

}