Problem Brief

Sum of All Values

FULLTIMEOA

A school in HackerLand organized a scholarship exam with this interesting mathematics problem on addition.

Given a string num that consists of digits ('0' to '9'), a '+' can be inserted between its characters. No adjacent '+' characters are allowed. The value of the expression is then evaluated. Find the sum of the values of all possible expressions after inserting '+' characters any number of times (possibly zero). Since the answer can be large, return the value modulo (10^9 + 7).

Function Description

Complete the function getExpressionSums in the editor below.

getExpressionSums has the following parameter(s):

1Example 1

Input

num = "123"

Output

168

Explanation

All possible valid expressions are shown.

"1 + 23", value = 24
"12 + 3", value = 15
"1 + 2 + 3", value = 6
"123", value = 123

Their sum is 24 + 15 + 6 + 123 = 168. Thus, the answer is 168 modulo (10^9 + 7) which is 168.

Constraints

Limits and guarantees your solution can rely on.

An unknown myth for now 🥲

Draft autosaves locally

public int getExpressionSums(String num) {
    // write your code here
}

Input

num

"123"

Output

168