Python While Loop, the and (&) operator is not working

Question

I am trying to find the greatest common factor. I wrote a bad (operation intensive) algorithm that decrements the lower value by one, checks using % to see if it evenly divides both the numerator and denominator, if it does then it exits the program. However, my while loop is not using the and operator, and thus once the numerator is divisible it stops, even though its not the correct answer. The numbers I am using are 54 and 42, the correct GCD (greatest common denominator) is 6. ``` #heres a simple algorithm to find the greatest common denominator: iterations = 0; #used to calculate number of times while loop is executed u = 54; v= 42; d = v-1; #u is the numerator, v is the denominator, d is the number decremented by one while ((v % d !=0) & (u % d != 0)): #while both numerator AND denominator cannot be evenly divided by the decremented number d -= 1 #decrement the number by one print d #print the number decremented iterations +=1 #add 1 to the count of iterations in while loop prin…

Accepted Answer

You should be using the keyword `and` instead of the bitwise and operator `&`:

```
while (v % d != 0) and (u % d != 0): 
```

This is also the same:

```
while (v % d) and (u % d): 
```

Note that `&` and `and` will give the same result in the first case, but not in the second.

Your problem though is that you want to use `or` instead of `and`. Also your algorithm is highly inefficient. There are better ways to calculate the GCD.

Python While Loop, the and (&) operator is not working

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