Garlic 2018 Waterloo Cup B Group simulation game (v) D. Code Blank: Fast Power

"topic link": https://nanti.jisuanke.com/t/25087

"Topic description":

The integer power of a number is often used in our calculations, but how can we work out the result in the time of O (log (n)).

The code in the Code box is an implementation, please analyze and fill in the missing code to find the result of X^y mod p.

Import java.util.*;
public class Main {
public static int pw (int x, int y, int p) {
if (y = = 0) {
return 1;
}
int res =//* Fill in the necessary code here */;
if ((Y & 1)!= 0) {
res = res * x% P;
}
return res;
}
public static void Main (string[] args) {
Scanner cin = new Scanner (system.in);
int x = Cin.nextint ();
int y = Cin.nextint ();
int p = cin.nextint ();
System.out.println (PW (x, Y, p));
}
}

"Answer": PW (x, Y/2, p) * PW (x, Y/2, p)% p

"Resolution":

"Code":

Import java.util.*;
public class Main {public
    static int pw (int x, int y, int p) {
        if (y = = 0) {return
            1;
        }
        int res = PW (x, Y/2, p) * PW (x, Y/2, p)% p/* fill in the necessary code here * * *;
        if ((Y & 1)!= 0) {
            res = res * x% P;
        }
        return res;
    }
    public static void Main (string[] args) {
        Scanner cin = new Scanner (system.in);
        int x = Cin.nextint ();
        int y = Cin.nextint ();
        int p = cin.nextint ();
        System.out.println (PW (x, Y, p));
    }