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.
使用递归实现深度搜索
public int sumNumbers(TreeNode root) {
if(root==null)return 0;
return dfs(root,0,0);
}
private int dfs(TreeNode node,int num,int sum){
if(node==null)return sum;
num=num*10+node.val;
if(node.left==null&&node.right==null){
sum+=num;
return sum;
}
sum=dfs(node.left,num,sum)+dfs(node.right,num,sum);
return sum;
}