基本大数问题

//N！
#include<iostream>
#include<cstdio>
#include<cstring>
#define ll long long 
#define  M 100000000
#define  N  50000//根据数据量选择
using namespace std;
ll n;
ll  a[N];//要用ll
void solve(ll n)
{
    memset(a,0,sizeof(a));
    a[0]=1;
    ll m=0;
    for(ll i=1;i<=n;i++)
    {
        for(ll j=0;j<=m;j++){
            a[j]*=i;//可能会超int
            if(j>=1&&a[j-1]>=M){
                a[j]+=a[j-1]/M;
                a[j-1]%=M;
            }
            if(a[m]>=M) m++;
        }
    }
    printf("%lld",a[m]);
    for(int i=m-1;i>=0;i--){
        printf("%08lld",a[i]);
    }
    printf("
");
}
int main()
{
    while(~scanf("%lld",&n)){
        solve(n);
    }
    return 0;
}

//N的阶乘
import java.math.BigInteger;
import java.util.Scanner;
public class d {
     static BigInteger x=BigInteger.valueOf(1);//要静态变量
    public static BigInteger getTac(BigInteger a)
    {
        if(a.compareTo(x) <= 0)//0！==1！==1
            return x;
        else
            return a.multiply(getTac(a.subtract(x)));
    }
    public static void main(String[] args) {
      
        Scanner cin = new Scanner(System.in);
        BigInteger m;
        while(cin.hasNext())
        {
            m = cin.nextBigInteger();
            m = getTac(m);
            System.out.println(m);
        }

    }
}        

//2^n大数
//C++
#include<iostream>
#include<cstdio>
#include<cstring>
#define  M 100000000
#define  N  500
using namespace std;
int a[N],t;
int n;
void solve(int n)
{
    memset(a,0,sizeof(a));//会对下次的运算造成影响
    a[0]=1;
    int m=0;
    for(int i=1;i<=n;i++)
    {
        for(int j=0;j<=m;j++)
        {
            a[j]<<=1;
            if(j>=1&&a[j-1]>=M){
                a[j]+=a[j-1]/M;
                a[j-1]%=M;
            }
            if(a[m]>=M) m++;
        }
    }
    printf("%d",a[m]);
    for(int i=m-1;i>=0;i--){
        printf("%08d",a[i]);
    }
    printf("
");
}
int main()
{
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        solve(n);
    }
    return 0;
}

//2^n
import  java.io.*;
import  java.util.*;
import  java.math.*;
public class Main{
    static Scanner cin = new Scanner(System.in);//写在main外面要静态
    public static void main(String args[]){
        int t;
        t=cin.nextInt();
        while(t>0){
            t=t-1;
            int n;
            n=cin.nextInt();
            BigInteger ans=BigInteger.valueOf(2);
            ans=ans.pow(n);
            System.out.println(ans);
        }
    }
}

//基础的java运算
import java.util.Scanner;
import java.math.BigInteger;
  public class Main{
    static Scanner cin=new Scanner(System.in);
    public static void main(String arg[]){
    BigInteger a,b;
    a=cin.nextBigInteger();
    b=cin.nextBigInteger();
    System.out.println("a+b :"+a.add(b));//+
    System.out.println(a.subtract(b)); // -
    System.out.println(a.multiply(b)); //*
    System.out.println(a.divide(b));  // /
    System.out.println(a.remainder(b)); // %
    if(a.equals(b)){
        System.out.println("YES");
    }
    else{
        System.out.println("NO");
    }
    if(a.compareTo(b)==0){
        System.out.println("a==b");
    }
    else if(a.compareTo(b)==-1){
        System.out.println("a<b");
    }
    else  if(a.compareTo(b)==1){
        System.out.println("a>b");
    }
}
}