问题描写叙述：

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.

For example:

Given the below binary tree and

sum = 22,

5             / \            4   8           /   / \          11  13  4         /  \    / \        7    2  5   1

return

[   [5,4,11,2],   [5,8,4,5]]

public class TreeNode {	      int val;	      TreeNode left;	      TreeNode right;	      TreeNode(int x) { val = x; }	 }		public List
     
      
       > pathSum(TreeNode root, int sum) {		if(root == null)    		return new ArrayList();				List
       
        
         > result = new LinkedList
         
          
           >(); List
           
             list = new LinkedList
            
             (); getPathNum(root, sum,list,result); return result; } public void getPathNum(TreeNode root, int sum,List
             
               list,List
              
               
                > result){ if(root.left == null && root.right ==null){ if(sum == root.val){ List
                
                  tmp = new LinkedList
                 
                  (list); tmp.add(root.val); result.add(tmp); return; } else return; } list.add(root.val); List
                  
                    ltmp = new LinkedList
                   
                    (list); List
                    
                      rtmp = new LinkedList
                     
                      (list); if(root.left !=null) getPathNum(root.left, sum-root.val,ltmp,result); if(root.right !=null) getPathNum(root.right, sum-root.val,rtmp, result); }