Ultraviolet A 10759 Dice Throwing

UVA_10759

We may think of N shards as throwing in sequence, so that at most 6 ^ N states can be represented by long, it is easier for us to use DP to find the total number of States not greater than X, so that we can divide them after calculation.

#include<stdio.h>
#include<string.h>
int N, X;
long long int f[30][160];
long long int gcd(long long int x, long long int y)
{
return y == 0 ? x : gcd(y, x % y);
}
void solve()
{
int i, j, k, p;
long long int a, b, c;
    memset(f, 0, sizeof(f));
for(j = 1; j <= 6; j ++)
for(k = j + 1; k <= X; k ++)
            f[1][k] += 1;
for(i = 2; i <= N; i ++)
for(j = 1; j <= 6; j ++)
for(k = j + 2; k <= X; k ++)
                f[i][k] += f[i - 1][k - j];
    b = 1;
for(i = 1; i <= N; i ++)
        b *= 6;
    a = b - f[N][X];
    c = gcd(b, a);
    a /= c, b/= c;
if(a == 0)
        printf("0\n");
else if(b == 1)
        printf("1\n");
else
        printf("%lld/%lld\n", a, b);
}
int main()
{
for(;;)
    {
        scanf("%d%d", &N, &X);
if(!N && !X)
break;
        solve();
    }
return 0;
}