题目描述
Samantha and Sam are playing a numbers game. Given a number as a string, no leading zeros, determine the sum of all integer values of substrings of the string.
Given an integer as a string, sum all of its substrings cast as integers. As the number may become large, return the value modulo $10^9+7$.
Example
$n=\text{'}42\text{'}$
Here $n$ is a string that has $3$ integer substrings: $\begin{array}{c}A\end{array}$, $2$, and $\textbf{42}$. Their sum is $48$, and $48\ \text{modulo}\ (10^9+7)=48$.
Function Description
Complete the substrings function in the editor below.
substrings has the following parameter(s):
string n: the string representation of an integer
Returns
int: the sum of the integer values of all substrings in $n$, modulo $10^9+7$
Input Format
A single line containing an integer as a string, without leading zeros.
Constraints
$1\leq ncastas an integer\leq2\times10^5$
Sample Input 0
16
Sample Output 0
23
Explanation 0
The substrings of 16 are 16, 1 and 6 which sum to 23.
Sample Input 1
123
Sample Output 1
164
Explanation 1
The substrings of 123 are 1, 2, 3, 12, 23, 123 which sum to 164.
输入格式
见题面
输出格式
见题面