进制转换（基础）

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    cin>>n;
    int s[100];
    int flag=0;
    while(n)
    {
        s[flag]=n%2;
        n=n/2;
        flag++;
    }
    for(int i=flag-1;i>=0;i--)
        cout<<s[i]<<endl;
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
    string s;
    cin>>s;
    long long int sum=0;
    int t;
    int p=1;
    for(int i=s.size()-1;i>=0;i--)
    {
        t=(s[i]-'0')*p;
        sum+=t;
        p=p*2;
    }
    cout<<sum<<endl;
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    cin>>n;
    int flag=0;
    int s[100];
    while(n)
    {
        s[flag++]=n%8;
        n=n/8;
    }
    for(int i=flag-1;i>=0;i--)
        cout<<s[i]<<endl;
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
char num[7] = {'A','B','C','D','E','F','G'};
int main()
{
    int n;
    cin>>n;
    int flag=0;
    char s[100];
    while(n)
    {
        int x=n%16;
        if(x>9)
        {
            s[flag++]=num[x-10];
        }
        else
            s[flag++]=(x+'0');
        n=n/16;
    }
    for(int i=flag-1;i>=0;i--)
        cout<<s[i]<<endl;
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
    string s;
    cin>>s;
    long long sum=0;
    int t;
    int p=1;
    for(int i=s.size()-1;i>=0;i--)
    {
        t=(s[i]-'0')*p;
        sum+=t;
        p=p*8;
    }
    cout<<sum<<endl;
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
    string s;
    cin>>s;
    unsigned long long p=1,sum=0;
    for(int i=s.size()-1;i>=0;i--)
    {
        if(s[i]>='0'&&s[i]<='9')
            sum+=(s[i]-'0')*p;
        else
            sum+=(s[i]-'A'+10)*p;
        p=p*16;
    }
    cout<<sum<<endl;
}