DouKaku?

using System;
static class Program {
    static void Main() {
        Console.WriteLine(Bin(01001001));   // 73
        Console.WriteLine(Bin(01101001));   // 105
    }
    static int Bin(uint octet) {
        int digit = 1, bin = 0;
        while(octet != 0) {
            if ((octet % 10) != 0) bin |= digit;
            digit <<= 1;
            octet /= 10;
        }
        return bin;
    }
}