Sum Root to Leaf Numbers

题目原型：

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.

基本思路：

本题的意思就是把每条路径代表的值想加，关键就是求路径。

	public List<Integer> list = new ArrayList<Integer>();
	public int sumNumbers(TreeNode root) 
	{
		if(root==null)
			return 0;
		int sum = 0;
		search(root, "");
		for(Integer in : list)
		{
			sum+=in;
		}
		return sum;
    }
	
	public void search(TreeNode root,String str)
	{
		if(root.left==null&&root.right==null)
		{
			str = str + root.val;
			list.add(Integer.parseInt(str));
		}
		else
		{
			if(root.left!=null)
				search(root.left, str+root.val);
			if(root.right!=null)
				search(root.right, str+root.val);
		}
	}

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Sum Root to Leaf Numbers

原文：http://blog.csdn.net/cow__sky/article/details/20566053