题解 | #10进制 VS 2进制#

#include <iostream>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

vector<int> bas_change(vector<int> A, int ob, int nb)
{
    vector<int> C;
    vector<int> D;
    while (A[0] != 0 || A.size() > 1)
    {
        int r = 0;
        for (int i = A.size() - 1; i >= 0; --i)
        {
            r = r * ob + A[i];
            C.push_back(r / nb);
            r %= nb;
        }
        reverse(C.begin(), C.end());
        while (C.size() > 1 && C.back() == 0)
            C.pop_back();

        A = C;
        C.clear();
        D.push_back(r);
    }
    return D;
}

int main()
{
    string a;
    cin >> a;
    vector<int> A;
    for (int i = a.size() - 1; i >= 0; --i)
        A.push_back(a[i] - '0');
    auto res = bas_change(A, 10, 2);
    reverse(res.begin(), res.end());
    auto ans = bas_change(res, 2, 10);
    for (int i = ans.size() - 1; i >= 0; --i)
        cout << ans[i];
    return 0;
}