hdu5187 java快速幂
特判n==1
1 import java.io.*; 2 import java.math.*; 3 import java.util.*; 4 import java.text.*; 5 6 public class mydo { 7 public static void main(String[] args) { 8 Scanner cin = new Scanner(System.in); 9 BigInteger a,b, m, ans; 10 while (cin.hasNext()) { 11 ans = new BigInteger("1"); 12 a = new BigInteger("2"); 13 b = cin.nextBigInteger(); 14 m = cin.nextBigInteger(); 15 if (b.compareTo(ans)==0) {System.out.println(ans.mod(m)); continue; } 16 a = a.mod(m); 17 while (b.compareTo(new BigInteger("0")) > 0) { 18 if (b.mod(BigInteger.valueOf(2)).compareTo(BigInteger.ONE) == 0) // if(n%2==1) 19 ans = ans.multiply(a).mod(m); // sq=(sq*p)%m; 20 a = a.multiply(a).mod(m); // p=(p*p)%m; 21 b = b.divide(BigInteger.valueOf(2)); 22 } 23 a = new BigInteger("2"); 24 ans=ans.add(m); 25 ans=ans.subtract(a); 26 System.out.println(ans.mod(m)); 27 } 28 } 29 }
