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.
1 class Solution { 2 public int sumNumbers(TreeNode root) { 3 return sum(root,0); 4 } 5 private int sum(TreeNode root,int s) { 6 //s 上一层的累积和 7 if(root==null) return 0; 8 if(root.left==null && root.right==null) //遍历到叶子节点 9 return s*10+root.val; 10 return sum(root.left,s*10+root.val)+sum(root.right,s*10+root.val); 11 } 12 }