Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.

sumNumbers.java

/*
Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.

An example is the root-to-leaf path 1->2->3 which represents the number 123.

Find the total sum of all root-to-leaf numbers.

For example,

    1
   / \
  2   3
The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.

Return the sum = 12 + 13 = 25.
*/

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    ArrayList<ArrayList<Integer>> set = new ArrayList<ArrayList<Integer>>();
    public int sumNumbers(TreeNode root) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if(root == null) return 0;
        set.clear();
        
        ArrayList<Integer> arys = new ArrayList<Integer>();
        getPathNumbers(arys, root);
        ArrayList<Integer> arySum = new ArrayList<Integer>();
        
        for(int i = 0; i < set.size(); i++) {
            arySum.add(buildNum(set.get(i)));
        }
        
        int ret = 0;
        for(int i = 0; i < arySum.size(); i++) {
            ret += arySum.get(i);
        }
        
        return ret;
    }
    
    public void getPathNumbers(ArrayList<Integer> arys, TreeNode root) {
        if(root.left == null && root.right == null) {
            arys.add(root.val);
            set.add(new ArrayList<Integer>(arys));
        } else {
            arys.add(root.val);
            if(root.left != null) {
                getPathNumbers(arys, root.left);
                arys.remove(arys.remove(arys.size() - 1));
            }
            if(root.right != null) {
                getPathNumbers(arys, root.right);
                arys.remove(arys.remove(arys.size() - 1));
            }
        }
    }
    
    public int buildNum(ArrayList<Integer> list) {
        int sum = 0;
        for(int i = 0; i < list.size(); i++) {
            sum = sum * 10 + list.get(i);
        }
        return sum;
    }
}

No working for "{2,1,#,4,#,7,#,4,#,8,#,3,#,6,#,4,#,7}";