AOJ 0030 Sum of Integersです。
import java.util.Scanner;
public class Main {
private static Scanner s = new Scanner(System.in);
public static void main(String[] args) {
while (true) {
int[] in = nextInput();
if (in[0] == 0 && in[1] == 0) {
break;
}
System.out.println(soi(in[0], in[1], -1));
}
}
static int soi(int n, int s, int i) {
if (n == 0) {
return (s == 0) ? 1 : 0;
}
int a = 0;
int l = Math.min(s, 9);
for (i = i + 1; i <= l; i++) {
a += soi(n - 1, s - i, i);
}
return a;
}
static int[] nextInput() {
int[] input = new int[2];
for (int i = 0; i < 2; i++) {
input[i] = s.nextInt();
}
return input;
}
}