Fizz Buzz

Fizz Buzz. A “classic” programming interview question.

The Question

Given all the numbers 1 through 100:

• If the number is a multiple of 3, print “Fizz” to the screen
• If the number is a multiple of 5, print “Buzz” to the screen
• If neither of the above is true, print the number to the screen

It is important to realize that there are a few special cases:

• What happens when the number is a multiple of 3 and 5?
• What would happen if you include 0 on the list?

The Answer

The implementation I wrote which I like the best is as follows.

Iterate from 1 to 100, then for each number, check for multiples using if test statements. Note that the statements cannot be nested, else for multiples of both 3 and 5, the statement will exit after the first statement is true.

#!/bin/bash
#set -xv
for i in {1..100}
do
     if [[ $(( $i % 3 )) == 0 ]]; then echo "Fizz"; fi
     if [[ $(( $i % 5 )) == 0 ]]; then echo "Buzz"; fi
     if [[ $(( $i % 3 )) != 0 && $(( $i % 5)) != 0 ]]; then echo "$i"; fi
done

Running the script is the same as running any script. First, make the file executable

chmod +x fizz_buzz

Second, run it.

./fizz_buzz

The output should look like this (only the first 20 entries shown)

1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
Fizz
Buzz
16
17
Fizz
19
Buzz

In an alternate version, at the start of the for-do-loop, you can use a “3rd-party” variable which eliminates the need for the huge test in the 3rd if statement.

#!/bin/bash
#set -xv
for i in {1..100}
do
     var=""
     if [[ $(( $i % 3 )) == 0 ]]; then var="Fizz" && echo "$var"; fi
     if [[ $(( $i % 5 )) == 0 ]]; then var="Buzz" && echo "$var"; fi
     if [[ "$var" == "" ]]; then echo "$i"; fi
done

Finally, using a case statement, which is very ugly since you have to correctly handle when the number is a multiple of 3 and 5.

#!/bin/bash
#set -xv
for i in {1..100}
do
     var=$(( $i % 3 ))
     case $var in 
          0)   echo "Fizz"
               var2=$(( $i % 5))
               case $var2 in
                    0) echo "Buzz";;
                    *) ;;
               esac;; 

          *)   var2=$(( $i % 5))
               case $var2 in
                    0) echo "Buzz";;
                    *) echo "$i";;
               esac 
     esac
done