Problem:
Score : 200 points

Problem Statement

Find the sum of the integers between 1 and N (inclusive), whose sum of digits written in base 10 is between A and B (inclusive).

Constraints

1 \leq N \leq 10^4

1 \leq A \leq B \leq 36

All input values are integers.

Input

Input is given from Standard Input in the following format:

N A B

Output

Print the sum of the integers between 1 and N (inclusive), whose sum of digits written in base 10 is between A and B (inclusive).

Sample Input 1

20 2 5

Sample Output 1

84

Among the integers not greater than 20, the ones whose sums of digits are between 2 and 5, are: 2,3,4,5,11,12,13,14 and 20. We should print the sum of these, 84.

Sample Input 2

10 1 2

Sample Output 2

13

Sample Input 3

100 4 16

Sample Output 3

4554

Solution in Go (1.6) (judge verdict: Accepted)

package main

import "fmt"

func main() {
	var n, a, b int

	fmt.Scan(&n, &a, &b)

	var result int
	for i := 0; i <= n; i++ {
		digitSum := digitSum(i)
		if a <= digitSum && digitSum <= b {
			result += i
		}
	}
	fmt.Println(result)
}

func digitSum(n int) int {
	var sum int

	for {
		digit := n % 10
		sum += digit
		if n/10 == 0 {
			break
		}
		n = n / 10
	}

	return sum
}