大数类题目——————JAVA实现

比眉伴天荒 2022-04-22 06:46 206阅读 0赞

# [HDU 1002 A + B Problem II][HDU 1002 A _ B Problem II] #

直接写就好了，不过格式有些麻烦

import java.math.*;
    import java.util.*;
    public class Main{
        
    	public static void main(String[] args){
        
    		Scanner cin = new Scanner(System.in);
    		int t = cin.nextInt();
    		int num = 1;
    		int x=0;
    		while(t>0){
        
    			if(x!=0)	System.out.println("");
    			else x=1;
    			BigInteger a = cin.nextBigInteger();
    			BigInteger b = cin.nextBigInteger();
    			System.out.println("Case "+num+":");
    			System.out.println(a+" + "+b+" = "+a.add(b));
    //			System.out.println("Case "+num+":\n"+a+" + "+b+" = " +a.add(b));
    			//写着一句话Wa了好多次，我现在有些怀疑println和"\n"不一样。
    			num++;			
    			t--;
    		}
    	}
    }

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# [POJ 2506 Tiling][] #

推出公式：  
 d p \[ n \] = d p \[ n − 1 \] + 2 ∗ d p \[ n − 2 \] \\Large dp\[n\]=dp\[n-1\]+2\*dp\[n-2\] dp\[n\]=dp\[n−1\]\+2∗dp\[n−2\]

不过JAVA写大数还真是方便 因为懒

import java.util.*;
    import java.math.*;//得有这个库
    public class Main{
        
    	public static void main(String[] agrs){
        
    		Scanner cin = new Scanner(System.in);
    		BigInteger[] a = new BigInteger[300];//定义大数数组
    		a[0] = BigInteger.ONE;//初始化
    		a[1] = BigInteger.ONE;//初始化
    		a[2] = a[1].add(a[0].add(a[0])); 
    		for(int i=3;i<=299;i++)
    			a[i] = a[i-1].add(a[i-2].add(a[i-2]));
    		while(cin.hasNext()){
        
    			int n = cin.nextInt();
    			System.out.println(a[n]);
    		}
    	}		
    }

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# [HDU 1042 N!][HDU 1042 N] #

求最大是 10000! 肯定得用大数来解决

import java.math.*;
    import java.util.*;
    public class Main{
        
        public static void main(String[] args){
        
            Scanner cin = new Scanner(System.in);
            BigInteger n;
            while(cin.hasNext()){
        
                int x = cin.nextInt();
                n = BigInteger.ONE;//初始化为1
                for(int i=1;i<=x;i++)
                    n = n.multiply(BigInteger.valueOf(i));
                System.out.println(n);
            }
        }
    }

--------------------

# [HDU 1047 Integer Inquiry][] #

多个大数相加，不过哦需要注意一下输入输出格式，  
n组数据，每两个输出之间有一个空行

import java.math.*;
    import java.util.*;
    public class Main{
        
        public static void main(String[] args){
        
            Scanner cin = new Scanner(System.in);
            int n = cin.nextInt();
            while(n-->0){
        
                BigInteger ans = BigInteger.ZERO;
                BigInteger x;
                while(cin.hasNextBigInteger()){
        
                    x = BigInteger.ZERO;
                    x = cin.nextBigInteger();
                    if(!x.equals(BigInteger.valueOf(0)))
                        ans = ans.add(x);
                    else{
        
                        System.out.println(ans);
                        if(n!=0)
                            System.out.println("");
                        break;
                    }
                }
            }
            System.gc();
        }
    }

--------------------

# [HDU 1715 大菲波数][HDU 1715] #

import java.math.*;
    import java.util.*;
    public class Main{
        
        public static void main(String[] args){
        
            Scanner cin = new Scanner(System.in);
            BigInteger[] a;
            a = new BigInteger[2000];
            a[0] = BigInteger.ZERO;
            a[1] = BigInteger.ONE;
            for(int i=2;i<1005;i++)
                a[i] = a[i-1].add(a[i-2]);
            int  n = cin.nextInt();
            while(n-->0){
        
                int i = cin.nextInt();
                System.out.println(a[i]);
            }
        }
    }

--------------------

# [HDU 1063 Exponentiation][] #

浮点数的幂，需要注意输出格式  
**0.123** 输出为 **.123**

import java.math.*;
    import java.util.*;
    
    public class Main{
        
        public static void main(String[] args){
        
            Scanner cin = new Scanner(System.in);
            while(cin.hasNext()){
        
                BigDecimal a = cin.nextBigDecimal();//输入大浮点数
                int n = cin.nextInt();
                String res = a.pow(n).stripTrailingZeros().toPlainString();//去掉整数后的小数点和多余的0
                if(res.startsWith("0"))
                    res = res.substring(1);    //去掉前导0                    
                System.out.println(res);
            }
        }
    }

--------------------

# [HDU 1753 大明A+B][HDU 1753 _A_B] #

大浮点数相加

import java.util.*;
    import java.math.*;
    public class Main{
        
        public static void main(String[] args){
        
            Scanner cin = new Scanner(System.in);
            BigDecimal a,b;
            while(cin.hasNext()){
        
                a = cin.nextBigDecimal();
                b = cin.nextBigDecimal();
                String res = a.add(b).stripTrailingZeros().toPlainString();
                System.out.println(res);
            }
        }
    }

--------------------

# [HDU 1316 How Many Fibs?][HDU 1316 How Many Fibs] #

求区间【a,b】中有多少个斐波那契数

import java.util.*;
    import java.math.*;
    public class Main{
        
        public static void main(String[] args){
        
            Scanner cin = new Scanner(System.in);
            BigInteger[] a  = new BigInteger[3000];
            a[0] = new BigInteger("1");
            a[1] = new BigInteger("1");
            for(int i=2;i<=500;i++)
                a[i] = a[i-1].add(a[i-2]);
            BigInteger x, y;
    
            while(cin.hasNext()){
        
                x = cin.nextBigInteger();
                y = cin.nextBigInteger();
                if(x.compareTo(BigInteger.ZERO)==0 && y.compareTo(BigInteger.ZERO)==0)    break;
                int ans = 0;
                for(int i=1;i<=500;i++){
        
                    if(x.compareTo(a[i]) <= 0 && y.compareTo(a[i]) >= 0)    ans++;
                    if(y.compareTo(a[i]) < 0)    break;
                }    
                System.out.println(ans);
            }
        }
    }

[HDU 1002 A _ B Problem II]: http://acm.hdu.edu.cn/showproblem.php?pid=1002
[POJ 2506 Tiling]: http://poj.org/problem?id=2506
[HDU 1042 N]: http://acm.hdu.edu.cn/showproblem.php?pid=1042
[HDU 1047 Integer Inquiry]: http://acm.hdu.edu.cn/showproblem.php?pid=1047
[HDU 1715]: http://acm.hdu.edu.cn/showproblem.php?pid=1715
[HDU 1063 Exponentiation]: http://acm.hdu.edu.cn/showproblem.php?pid=1063
[HDU 1753 _A_B]: http://acm.hdu.edu.cn/showproblem.php?pid=1753
[HDU 1316 How Many Fibs]: http://acm.hdu.edu.cn/showproblem.php?pid=1316