题解 | 进制转换2

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

typedef long long ll;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    ll M, N;
    string s;
    string fin;
    cin >> M >> N >> s;
    ll n = s.length();
    ll sum = 0;
    for(ll i = 0; i < n; i++){
        if(s[i] >= 'A' && s[i] <= 'Z') sum = sum * M + (s[i] - 'A') + 10;
        else sum = sum * M + (s[i] - '0');
    }
    ll x;
    while(sum > 0){
        x = sum % N;
        sum = sum / N;
        if(x < 10) fin.push_back(x + '0');
        else fin.push_back('a' + x - 10);
    }
    reverse(fin.begin(), fin.end());
    cout << fin;
    return 0;
}