蓝桥杯省赛无忧 第二章 基础算法 课件25 进制转换

01 进制的本质

02 将任意进制转换为十进制

03 将十进制转换为任意进制

04 例题讲解

#include <bits/stdc++.h>
using namespace std;
const int N=66;
int a[N];
int main()
{
 string s="2021ABCD";
 for(int i=0;i<s.length();++i)
 {
   if((s[i]>='0')&&(s[i]<='9'))
   a[i]=s[i]-'0';
   else
   a[i]=s[i]-'A'+10;
 } 
 long long x=0;
 for(int i=0;i<s.length();++i)
 {
   x=x*16+a[i];
 }
 cout<<x;
  return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
  int a,b,c,d,e;
  int sum;
  a=2022;
b=a/1000;
c=a/100%10;
d=a/10%10;
e=a%10;
sum=pow(9,3)*b+pow(9,2)*c+pow(9,1)*d+pow(9,0)*e;
printf("%d",sum);
  return 0;
}

#include<bits/stdc++.h>
using namespace std;
const int N=1000;
using ll=long long;
int a[N];
char ch[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
void solve(){
  int n,m;cin>>n>>m;
  string s;cin>>s;
  int len=s.length();
  s="#"+s;
  for(int i=1;i<=len;i++){
    if(s[i]<='9'&&s[i]>='0')a[i]=s[i]-'0';
    else a[i]=s[i]-'A'+10;
  }
  ll x=0;
  for(int i=1;i<=len;i++){
    x=x*n+a[i];
  }
  string ans;
  while(x){
   ans+=ch[x % m];
    x/=m;
  }
  reverse(ans.begin(),ans.end());
  cout<<ans<<"\n";
  
}
int main(){
  ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
  int t;cin>>t;
  while(t--){
    solve();
  }
  return 0;
}