1457. 二叉树中的伪回文路径 --力扣 --JAVA

class Solution {
    private int ans = 0;
    public int pseudoPalindromicPaths (TreeNode root) {
        Map<Integer,Integer> data = new HashMap<>();
        countPath(root, data);
        return ans;
    }
    public void countPath(TreeNode root, Map<Integer,Integer> data){
        if(root != null) {
            if (data.get(root.val) != null) {
                data.remove(root.val);
            } else {
                data.put(root.val, 0);
            }
            if (root.left == null && root.right == null) {
                if (data.size() == 1 || data.size() == 0) {
                    ans++;
                }
            } else {
                if(root.left != null) {
                    countPath(root.left, new HashMap<>(data));
                }
                if(root.right != null) {
                    countPath(root.right, new HashMap<>(data));
                }
            }
        }
    }
}