34、二叉树中和为某一值的路径 //代码未通过

import java.util.ArrayList;
/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

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

    }

}
*/
public class Solution {
    public ArrayList<ArrayList<Integer>> FindPath(TreeNode root, int target) {

        //鲁棒性校验
        if (root == null) {
            return null;
        }
        //定义辅助栈，这里用ArrayList来代替，因为使用stack只能获取栈顶元素，我们要存储的是所有元素，存储遍历路径
        ArrayList<Integer> path = new ArrayList<Integer>();
        int currentSum = 0;
        ArrayList<ArrayList<Integer>> pathList = new ArrayList<ArrayList<Integer>>();
        FindPath(root, target, path, currentSum, pathList);

        return pathList;
    }

    public void FindPath(TreeNode root, int target, ArrayList<Integer> path, int currentSum, ArrayList<ArrayList<Integer>> pathList) {
        currentSum += root.val;
        path.add(root.val);
        //若是叶子节点，且路径上的节点值的和等于目标值，则存储这条路径
        boolean isLeaf=false;
        if(root.left == null && root.right == null){
            isLeaf=true;
        }

        if (currentSum == target && isLeaf==true) {
            pathList.add(path);
        }

        //若不是叶子节点，则遍历其所有子节点
        if (root.left != null) {
            FindPath(root.left, target, path, currentSum, pathList);
        }
        if (root.right != null) {
            FindPath(root.right, target, path, currentSum, pathList);
        }
        
        //返回父节点前，在路径上删掉当前节点
        int tailIndex=path.size()-1;
        path.remove(tailIndex);

    }
}