Java 大数的几道题目 nyist

import java.math.BigInteger;
import java.util.*;
/**
* nyist 28
* 大数阶乘
*/
public class Main28 {
public static void main(String args[]) {
Scanner cin = new Scanner(System.in);
int n = cin.nextInt();
BigInteger ans = BigInteger.ONE;
for (int i = 1; i <= n; ++i)
ans = ans.multiply(BigInteger.valueOf(i));
System.out.println(ans);
}
}
import java.math.BigInteger;
import java.util.Scanner;
public class Main103 {
public static void main(String[] args) {
Scanner cin = new Scanner(System.in);
int T = cin.nextInt();
for (int i = 1; i <= T; i++) {
BigInteger a = cin.nextBigInteger();
BigInteger b = cin.nextBigInteger();
System.out.println("Case " + i + ":");
System.out.println(a + " + " + b + " = " +a.add(b));
}
}
}
import java.math.BigDecimal;
import java.util.*;
/* poj 1001 nyist 155
*/
public class Main155 {
public static void main(String args[]) {
Scanner cin = new Scanner(System.in);
while (cin.hasNext()) {    //  相当于c++的！=EOF。
BigDecimal ans = cin.nextBigDecimal();
int n = cin.nextInt();
String res = ans.pow(n).stripTrailingZeros().toPlainString(); // 整数去掉小数点和后面的0， 返回不带指数字段的此 BigDecimal 的字符串表示形式。
if (res.startsWith("0")) {  //去掉前导0
res = res.substring(1);
}
System.out.println(res);
}
}
}