Java大数类应用

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参考: 飘过的小牛“Java大数类练手” http://blog.csdn.net/niushuai666/article/details/6972991

1、nyoj-28 大数阶乘 (大数乘)

题目链接: http://acm.nyist.net/JudgeOnline/problem.php?pid=28

import java.math.BigInteger;import java.util.*;public class Main {public static void main(String args[]){Scanner cin = new Scanner(System.in);long num = cin.nextLong();BigInteger ans = new BigInteger("1");while(num > 0){ans = ans.multiply(BigInteger.valueOf(num));num -= 1;}System.out.println(ans);cin.close();}}

2、nyoj-45 棋盘覆盖 (大数幂, 大数减, 大数除)

题目链接: http://acm.nyist.net/JudgeOnline/status.php?pid=45

import java.math.BigInteger;import java.util.*;public class Main {public static void main(String args[]){Scanner cin = new Scanner(System.in);int loop = cin.nextInt();while(loop-- > 0){int k = cin.nextInt();BigInteger ans = new BigInteger("4");ans = ans.pow(k).subtract(BigInteger.valueOf(1)).divide(BigInteger.valueOf(3));System.out.println(ans);}}}

3、nyoj-73 比大小 (大数比较)

题目链接: http://acm.nyist.net/JudgeOnline/problem.php?pid=73

import java.math.BigInteger;import java.util.*;public class Main {public static void main(String args[]){Scanner cin = new Scanner(System.in);BigInteger a, b;while(true){a = cin.nextBigInteger();b = cin.nextBigInteger();if(a.equals(BigInteger.valueOf(0)) && b.equals(BigInteger.valueOf(0))){break;}int ans = a.compareTo(b);if(ans == 0){System.out.println("a==b");}else if(ans < 0){System.out.println("a<b");}else{System.out.println("a>b");}}}}

3、nyoj-103 A+B Problem II (大数加法)

题目链接: http://acm.nyist.net/JudgeOnline/problem.php?pid=103

import java.math.BigInteger;import java.util.*;public class Main {public static void main(String args[]){Scanner cin = new Scanner(System.in);BigInteger a, b, ans;int loop = cin.nextInt(), i = 0;while(i ++ < loop){a = cin.nextBigInteger();b = cin.nextBigInteger();ans = a.add(b);System.out.println("Case " + i + ":");System.out.println(a + " + " + b + " = " + ans);}}}

4、nyoj-114 某种序列(递推求值)

题目链接:http://acm.nyist.net/JudgeOnline/problem.php?pid=114

import java.math.BigInteger;import java.util.*;public class Main {public static void main(String args[]){Scanner cin = new Scanner(System.in);BigInteger ans[] = new BigInteger[100];while(cin.hasNext()){for(int i = 0; i < 3; i ++){ans[i] = cin.nextBigInteger();}for(int i = 3; i < 100; i ++){ans[i] = ans[i - 1].add(ans[i - 2].add(ans[i - 3]));}System.out.println(ans[99]);}}}

5、nyoj-155 高精度幂

题目链接: http://acm.nyist.net/JudgeOnline/problem.php?pid=155

import java.math.BigDecimal;import java.util.*;public class Main {public static void main(String args[]){Scanner cin = new Scanner(System.in);BigDecimal a;int b;while(cin.hasNext()){a = cin.nextBigDecimal();b = cin.nextInt();String ans = a.pow(b).stripTrailingZeros().toPlainString();// 整数去掉小数点和后面的0if(ans.startsWith("0")){ //去掉前导0                   ans = ans.substring(1);              }  System.out.println(ans);}}}

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