poj 1220 java大数类

题目链接：http://poj.org/problem?id=1220

还真不习惯。。。。。。

import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Scanner;

public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner input = new Scanner(System.in);
		int icase;
		int b1;
		int b2;
		String str;
		char ch;
		int top = 0;
		int c;
		char chh;
		int tmp;
		BigInteger sum,a;
		BigInteger t;
		int[] stack = new int[2000];
		// 余数入栈
		icase = input.nextInt();
		while ((icase--) != 0) {
			 a = BigInteger.valueOf(1);
			 sum = new BigInteger("0");
			b1 = input.nextInt();
			b2 = input.nextInt();
			str = input.next();
			for (int i = str.length()-1; i >= 0 ; i--) {   //先化成10进制
				tmp = 0;
				ch = str.charAt(i);
				if (ch <= '9' && ch >= '0') {
					tmp = ch - '0';
				} else if (ch >= 'A' && ch <= 'Z') {
					tmp = ch - 'A' + 10;
				} else if (ch >= 'a' && ch <= 'z') {
					tmp = ch - 'a' + 36;
				}
				sum = sum.add(BigInteger.valueOf(tmp).multiply(a));
				a = a.multiply(BigInteger.valueOf(b1));
			}
			System.out.print(b1 + " " + str + "\n" + b2 + " ");
			  BigInteger zero = BigInteger.valueOf(0); 
			  //sum != BigInteger.valueOf(0)这样不对  java不能这样比较两个对象是否相等吧
			  //神马都是类。。。。。。。。。。。。受不了，不习惯
			while (sum.compareTo(zero) != 0) {
				t = sum.mod(BigInteger.valueOf(b2));
				stack[++top] = t.intValue();
				sum = sum.divide(BigInteger.valueOf(b2));
			}
			if(top == 0)
				System.out.print(0);
			while (top != 0) {
				c = stack[top--];
				if (c < 10)
					chh = (char) (c + '0');
				else if (c < 36)
					chh = (char) (c - 10 + 'A');
				else
					chh = (char) (c - 36 + 'a');
				System.out.print(chh);
			}
			System.out.print("\n\n");
		}
	}

}