【剑指offer】十七，二叉树中和为某一值的路径

 1 import java.util.ArrayList;
 2 /**
 3 public class TreeNode {
 4     int val = 0;
 5     TreeNode left = null;
 6     TreeNode right = null;
 7  
 8     public TreeNode(int val) {
 9         this.val = val;
10  
11     }
12  
13 }
14 */
15 public class Solution {
16     public ArrayList<ArrayList<Integer>> FindPath(TreeNode root,int target) {
17          ArrayList<ArrayList<Integer>>  res = new ArrayList<ArrayList<Integer>> ();
18          ArrayList<Integer> path = new ArrayList<Integer>() ;
19          search(root ,target,res,path) ;
20          return res ;
21         }
22     private void search(TreeNode root, int target, ArrayList<ArrayList<Integer>>  res,ArrayList<Integer> path) {
23         if(root==null){
24             return ;
25         }
26         target = target - root.val ;
27         if(root.left == null && root.right == null){
28             if(target == 0){
29                 path.add(root.val);
30                 res.add(new ArrayList<Integer>(path));
31                 path.remove(path.size()-1);
32             }
33             return;
34         }
35         path.add(root.val )  ;
36         search(root.left,target,res,path) ;
37         search(root.right,target,res,path) ;
38         path.remove(path.size()-1) ;
39          
40     }
41 }