题解 | 进制转换

#include <iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
//采用引用可以避免拷贝
vector<int> div(vector<int>& a, int b, int& r) {
    int t = 0;
    vector<int>res;
    for (int i = a.size() - 1; i >= 0; i--) {
        int tmp = (t * 10+a[i]) / b;
        res.push_back(tmp);
        t = (t * 10 + a[i]) % b;
    }
    r = t;
    //翻转，处理前导0
    reverse(res.begin(), res.end());
    //由于要用试除法，所以这里判断条件要加等号
    while (res.size() >= 1 && res.back() == 0)res.pop_back();
    return res;
}

//高精度
int main() {
    string str;
    while (cin >> str) {
        vector<int>a;
        for (int i = str.size() - 1; i >= 0; i--) {
            a.push_back(str[i] - '0');
        }

        int r = 0;//引用传递传回余数
        vector<int>res;
        //然后写试除法
        while (!div(a, 2, r).empty()) {
            a = div(a, 2, r);
            res.push_back(r);
        }
        res.push_back(r);
        for (int i = res.size() - 1; i >= 0; i--) {
            cout << res[i];
        }
        puts("");
    }
}
// 64 位输出请用 printf("%lld")