Hdu4762cut the Cake (probability)

Topic Links:

http://acm.hdu.edu.cn/showproblem.php?pid=4762

Test instructions

Divide a prototype cake into an M-fan, and then make n strawberries happen on one of them.

Analysis:

We take one from the first to have n choices, and then the rest of the n-1 strawberry in the range of its polar angle [0,360/m].

The probability of a 1/m,n-1 is 1/m^ (n-1);

So the total probability is n/m^ (n-1). Because 20^20 exceeds longlong, high precision is required

The code is as follows:

Package Fuck;import Java.math.biginteger;import Java.util.scanner;public class Main {static BigInteger gcd ( BigInteger A,biginteger b) {if (!b.equals (Biginteger.zero)) return gcd (B,a.mod (b)); return A;}    public static void Main (String args[]) {          Scanner cin=new Scanner (system.in);          int t =  cin.nextint ();        while (t>0) {        int m = Cin.nextint ();        int n = cin.nextint ();        BigInteger n = biginteger.valueof (n);        BigInteger M = biginteger.valueof (M). Pow (n-1);        BigInteger tmp = GCD (n,m);        SYSTEM.OUT.PRINTLN (N.divide (TMP) + "/" +m.divide (TMP));        t--;}}}    

Hdu4762cut the Cake (probability)