1212번: 8진수 2진수

#include<iostream>
#include<string>
using namespace std;
int main()
{
    string oct;
    cin >> oct;
    if (oct == "0")
    {
        cout << oct;
        return 0;
    }
    bool isFirst = true;
    for (int i = 0, len = oct.length(); i < len; ++i)
    {
        int t = (int)oct[i] - '0';
        for (int j = 4; j; t %= j, j /= 2)
        {
            if (isFirst)
                if (t / j == 0)
                    continue;
            cout << t / j;
            if (isFirst)
                isFirst = false;
        }
    }
}