題目描述：

需要注意的是，樹的節點不一定都是正數，並且target也不一定是正數，意思就是當你只有執行到葉子節點時才能結束，否則還需要繼續
程式碼

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
   public static int count = 0;
  public static int pathSum(TreeNode root, int sum) {
		if(root == null){
			return 0;
		}
		if(root.left == null && root.right == null){
			if(root.val != sum){
				return 0;
			}else {
				return 1;
			}
		}
		Stack<TreeNode> tem = new Stack<>();
		tem.push(root);
		
		while (!tem.isEmpty()) {
		
			
			TreeNode s = tem.pop();
			find(s,sum,0);
			if(s.left != null){
				tem.push(s.left);
			}
			if(s.right != null){
				tem.push(s.right);
			}
		}		
		return Solution.count;
        
    }
	public  static void find(TreeNode treeNode,int exceptsum,int currentnum){
		
		if(treeNode.val + currentnum ==  exceptsum){
			Solution.count++;
		}
		
		if(treeNode.left != null){
			find(treeNode.left,exceptsum, currentnum + treeNode.val);
		}
		if(treeNode.right != null){
			find(treeNode.right,exceptsum, currentnum + treeNode.val);
		}
		
		
		
	}
}
 

奇怪的時同樣的測試用例執行沒問題，提交就出問題。。。

排名靠前的程式碼

class Solution {
    int path = 0;
    public int pathSum(TreeNode root, int sum) {
        path_sum(root,sum,new int[0]);
        return path;
    }
    public void path_sum(TreeNode node, int sum,int[] array){
        if(node == null) return ;
        int[] newArray= new int[array.length+1];
        for(int i = 0 ;i<array.length;i++){
            newArray[i] = array[i]+node.val;
            if(newArray[i] == sum) path+=1;
        }
        newArray[array.length] = node.val;
        if(node.val == sum) path+=1;
        if(node.left!=null) path_sum(node.left, sum, newArray);
        if(node.right!=null) path_sum(node.right, sum, newArray);
    }
}