549. Binary Tree Longest Consecutive sequence

给定一棵二叉树，求其最长连续数字路径（指的是形如x , x + 1 , x + 2 , . . . , x + k x,x+1,x+2,...,x+kx,x+1,x+2,...,x+k的路径）的长度。路径可以由任一点出发，任一点结束。

public class ShowMeBug {
    public static class TreeNode {
        public int val;
        public TreeNode left;
        public TreeNode right;

        public TreeNode(int val) {
            this.val = val;
        }
    }

    public static void main(String[] args) {
        TreeNode node1 = new TreeNode(4);
        TreeNode node2 = new TreeNode(2);
        TreeNode node3 = new TreeNode(5);
        TreeNode node4 = new TreeNode(1);
        TreeNode node5 = new TreeNode(3);
        node1.left = node2;
        node1.right = node3;
        node2.left = node4;
        node2.right = node5;
        ShowMeBug showMeBug = new ShowMeBug();
        int max = showMeBug.getTreeMaxSerLength(node1);
        System.out.println(max);
    }

    public int getTreeMaxSerLength(TreeNode root) {
        dfs(root, 1);
        return maxLength;
    }

    int maxLength = 1;

    public void dfs(TreeNode root, int length) {
        if (root == null) {
            return;
        }
        if (root.left != null) {
            if (root.left.val - root.val == 1) {
                maxLength = Math.max(maxLength, length + 1);
                dfs(root.left, length + 1);
            } else {
                dfs(root.left, 1);
            }
        }
        if (root.right != null) {
            if (root.right.val - root.val == 1) {
                maxLength = Math.max(maxLength, length + 1);
                dfs(root.right, length + 1);
            } else {
                dfs(root.right, 1);
            }
        }

    }

}

。。。