JAVA大数在ACM中应用

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HDU-1002

大数A+B

    import java.math.BigDecimal;    import java.math.BigInteger;    import java.util.*;    public class Main {        public static void main(String[] args) {            Scanner in = new Scanner(System.in);            int T;            T = in.nextInt();            for(int cas = 1;cas <= T;cas++ )            {                System.out.println("Case "+cas+":");                BigInteger a = in.nextBigInteger();                BigInteger b = in.nextBigInteger();                BigInteger c = a.add(b);                System.out.println(a+" + "+b+" = "+c);                if(cas!=T)System.out.println("");            }        }    }

HDU-1042(https://cn.vjudge.net/problem/HDU-1042)

求N!

import java.math.BigDecimal;import java.math.BigInteger;import java.util.*;public class Main {    public static void main(String[] args) {        Scanner in = new Scanner(System.in);        int T;        while(in.hasNext())        {            int n = in.nextInt();            BigInteger ans = new BigInteger("1");            for(int i=1;i<=n;i++)            {                BigInteger a=BigInteger.valueOf(i);                ans = ans.multiply(a);            }            System.out.println(ans);        }    }}

HDU - 1133
公式:(m+n)!*(m-n+1)/(m+1)

import java.math.BigDecimal;import java.math.BigInteger;import java.util.*;public class Main {    public static void main(String[] args) {        Scanner in = new Scanner(System.in);        int cas = 0;        while(in.hasNext())        {            cas++;            int m = in.nextInt();            int n = in.nextInt();            if(n==0&&m==0)            {                break;            }            if(m<n)            {                System.out.println("Test #"+cas+":");                System.out.println("0");                continue;            }            BigInteger ans = new BigInteger("1");            for(int i=1;i<=n+m;i++)            {                BigInteger a=BigInteger.valueOf(i);                ans = ans.multiply(a);            }            BigInteger a=BigInteger.valueOf(m-n+1);            ans = ans.multiply(a);            a=BigInteger.valueOf(m+1);            ans = ans.divide(a);            System.out.println("Test #"+cas+":");            System.out.println(ans);        }    }}

HDU - 1250
公式:F(1) = 1, F(2) = 1, F(3) = 1,F(4) = 1, F(n>4) = F(n - 1) + F(n-2) + F(n-3) + F(n-4)

import java.math.BigDecimal;import java.math.BigInteger;import java.util.*;public class Main {    public static void main(String[] args) {        Scanner in = new Scanner(System.in);        BigInteger f[] = new BigInteger[10005];        while(in.hasNext())        {            int n = in.nextInt();            f[1] = BigInteger.valueOf(1);            f[2] = BigInteger.valueOf(1);            f[3] = BigInteger.valueOf(1);            f[4] = BigInteger.valueOf(1);            for(int i=5;i<=n;i++)            {                f[i]=f[i-1].add(f[i-2]).add(f[i-3]).add(f[i-4]);            }            System.out.println(f[n]);        }    }}

HDU - 1297
f[i] = f[i - 1].add(f[i - 2]).add(f[i - 4]);

 import java.math.BigDecimal;import java.math.BigInteger;import java.util.*;public class Main {    public static void main(String[] args) {        Scanner in = new Scanner(System.in);        BigInteger f[] = new BigInteger[10005];        //f[n] = f[n - 1] + f[n - 2] + f[n - 4]        f[0] = BigInteger.valueOf(1);        f[1] = BigInteger.valueOf(1);        f[2] = BigInteger.valueOf(2);        f[3] = BigInteger.valueOf(4);        for(int i=4;i<=1000;i++)        {            f[i] = f[i - 1].add(f[i - 2]).add(f[i - 4]);        }        while(in.hasNext())        {            int n = in.nextInt();            System.out.println(f[n]);        }    }}

HDU - 1715

Fibonacci数列

import java.math.BigDecimal;import java.math.BigInteger;import java.util.*;public class Main {    public static void main(String[] args) {        Scanner in = new Scanner(System.in);        BigInteger f[] = new BigInteger[10005];        //f[n] = f[n - 1] + f[n - 2] + f[n - 4]        f[0] = BigInteger.valueOf(0);        f[1] = BigInteger.valueOf(1);        for(int i=2;i<=1000;i++)        {            f[i] = f[i - 1].add(f[i - 2]);        }        int T;        T = in.nextInt();        for(int cas=1;cas<=T;cas++)        {            int n = in.nextInt();            System.out.println(f[n]);        }    }}

HDU - 1753

import java.math.BigDecimal;import java.math.BigInteger;import java.util.*;public class Main {    public static void main(String[] args) {        Scanner in = new Scanner(System.in);        while(in.hasNext())        {            BigDecimal a  = in.nextBigDecimal();            BigDecimal b  = in.nextBigDecimal();            BigDecimal c  = a.add(b);            c = c.stripTrailingZeros();            String s=c.toPlainString();            System.out.println(s);        }    }}/*一个是 BigDecimal.stripTrailingZeros()，作用是将BigDecimal转化为最简形式（去掉末尾多余的0或小数点）还有 BigDecimal.toPlainString() ，作用是将BigDecimal转为字符串，因为小数位数过多的话会被输出成科学计数法表示，不希望那样的话就要用到这个方法； */

HDU - 1865

f[i] = f[i-1] + f[i-2]

import java.math.BigDecimal;import java.math.BigInteger;import java.util.*;public class Main {    public static void main(String[] args) {        Scanner in = new Scanner(System.in);        BigInteger f[] = new BigInteger[1000];        f[1] = BigInteger.valueOf(1);        f[2] = BigInteger.valueOf(2);        for(int i=3;i<=200;i++)        {            f[i] = f[i-1].add(f[i-2]);        }        int T;        T = in.nextInt();        for(int i=1;i<=T;i++)        {            String s = in.next();            System.out.println(f[s.length()]);        }    }}/*一个是 BigDecimal.stripTrailingZeros()，作用是将BigDecimal转化为最简形式（去掉末尾多余的0或小数点）还有 BigDecimal.toPlainString() ，作用是将BigDecimal转为字符串，因为小数位数过多的话会被输出成科学计数法表示，不希望那样的话就要用到这个方法； */

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