24.java

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 {
    //本质是一个深度优先遍历
    ArrayList<ArrayList<Integer>> result=new ArrayList<ArrayList<Integer>>();
    ArrayList<Integer> temp=new ArrayList<Integer>();
    public ArrayList<ArrayList<Integer>> FindPath(TreeNode root,int target) {
        if(root==null) return result;
        temp.add(root.val);
        target=target-root.val;
        if(target==0 && root.left==null && root.right==null) result.add(new ArrayList(temp));
        FindPath(root.left,target);
        FindPath(root.right,target);
        temp.remove(temp.size()-1);
        return result;
    }
}