Write a program with one & only if statement that [closed]

Question

Challenge: You Are The Teacher

Everyone knows that simple task of receiving a grade, and telling if the student:

is approved,

will attend the summer school, or

failed.

In this challenge, you must write a program that does that, but using the maximum of one if statement (also ternary operators count as if).

The grade will be an integer from 0 to 10.

situation   outputs
-------------------------
grade >= 7: Approved
grade >= 3: Summer School
grade  < 3: Failed

You can do whatever you want, write in any language.

Fastest working answer wins.

@Volatility Tricky and worky, but ew... let's think of something better =P ("Unfortunately" would still count as a correct answer) — BernaMariano, Jul 5 '13 at 5:45
This problem is far too trivial to be assessable on speed. To be able to compare performance with any confidence, you need the programs to run for a minute, not for about ten clock cycles. — Peter Taylor, Jul 5 '13 at 7:19

Cristian Lupascu · Accepted Answer · 2013-07-05 06:34:26Z

Ruby

def x(mark)
    possible_results = ['','Failed', 'Failed', 'Summer school', 'Approved']

    index = (mark + 1).to_s(2).length

    possible_results[index]
end

This uses the fact that the length of the binary representation of the numbers 0-10 is pretty close to the required classification.

Online test: http://ideone.com/y0kLqY

Howard · Accepted Answer · 2013-07-05 06:44:41Z

7

Ruby

Using regular expressions:

puts "Failed012Summer School3456Approved78910"[/\D*(?=\d*#{gets.chomp})/]

Plain array indexing:

puts ["Failed","Summer School","Approved"][(gets.to_i+1)/4]

edited Jul 5 '13 at 6:44

answered Jul 5 '13 at 6:34

Howard

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Bakuriu · Accepted Answer · 2013-07-05 16:10:32Z

Python2: 65

Bonus: it doesn't use any conditional expression.

g=input();print("Approved","Summer School","Failed")[(g<7)+(g<3)]

Example output:

>>> g=input();print("Approved","Summer School","Failed")[(g<7)+(g<3)]
10
Approved
>>> g=input();print("Approved","Summer School","Failed")[(g<7)+(g<3)]
7
Approved
>>> g=input();print("Approved","Summer School","Failed")[(g<7)+(g<3)]
6
Summer School
>>> g=input();print("Approved","Summer School","Failed")[(g<7)+(g<3)]
3
Summer School
>>> g=input();print("Approved","Summer School","Failed")[(g<7)+(g<3)]
2
Failed

Paul R · Accepted Answer · 2016-01-25 14:56:42Z

3

C

#include <stdio.h>
#include <stdlib.h>

int min(int a, int b)
{
    return (a < b) * a + (a >= b) * b;
}

const char *grade_to_string(int grade)
{
    const char * grades[3] = { "Failed", "Summer school", "Approved" };
    return grades[min(((grade + 1) >> 2), 2)];
}

int main(int argc, char *argv[])
{
    int grade = atoi(argv[1]);
    printf("%d = %s\n", grade, grade_to_string(grade));
    return 0;
}

Test:

$ gcc -Wall -O3 grade.c
$ time for i in $(seq -1 20) ; do ./a.out $i ; done
-1 = Failed
0 = Failed
1 = Failed
2 = Failed
3 = Summer school
4 = Summer school
5 = Summer school
6 = Summer school
7 = Approved
8 = Approved
9 = Approved
10 = Approved
11 = Approved
12 = Approved
13 = Approved
14 = Approved
15 = Approved
16 = Approved
17 = Approved
18 = Approved
19 = Approved
20 = Approved

real    0m0.120s
user    0m0.025s
sys     0m0.042s
$

edited Jan 25 '16 at 14:56

answered Jul 5 '13 at 7:29

Paul R

2,8931 gold badge14 silver badges21 bronze badges

\$\begingroup\$ I count one ternary operator and one if. \$\endgroup\$ – Peter Taylor Jul 5 '13 at 8:09
\$\begingroup\$ Well main is just a test harness, so I don't count the if in that - I'll remove it though if it makes you happy. ;-) \$\endgroup\$ – Paul R Jul 5 '13 at 9:42
\$\begingroup\$ The spec asks for a program, so I think you have to count main. It would be more interesting, though, to keep that if and remove the one in min ;) \$\endgroup\$ – Peter Taylor Jul 5 '13 at 9:51
1

\$\begingroup\$ Challenge accepted ! \$\endgroup\$ – Paul R Jul 5 '13 at 9:53

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breadbox · Accepted Answer · 2013-07-05 07:01:58Z

2

Perl

sub f {
  my $grade = shift;
  my $result = 0;
  for (++$grade ; $grade > 1; $grade >>= 1) {
    ++$result;
  }
  return ("Failed", "Failed", "Summer school", "Approved")[$result];
}

(The for-loop test constitutes the program's one permitted "if statement".)

answered Jul 5 '13 at 7:01

breadbox

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plannapus · Accepted Answer · 2013-07-05 07:19:25Z

R

g=function(x)cut(x,c(0,3,7,10),
                 labels=c("Failed","Summer school","Approved"),
                 right=FALSE, include=TRUE)

Usage:

> g(2)
[1] Failed
Levels: Failed Summer school Approved
> g(7)
[1] Approved
Levels: Failed Summer school Approved
> g(3)
[1] Summer school
Levels: Failed Summer school Approved

Function cut in R converts a numeric into a factor (categorical) according to the interval in which it falls. It is vectorized:

> g(0:10)
[1] Failed       Failed       Failed       Summer school Summer school Summer school Summer school
[8] Approved      Approved      Approved      Approved     
Levels: Failed Summer school Approved

manatwork · Accepted Answer · 2013-07-05 08:52:32Z

Awk

{
  print check($1,0,2,"Failed") check($1,3,6,"Summer School") check($1,7,10,"Approved")
}

function check(grade,lower,upper,result)
{
  if (grade>=lower && grade<=upper) return result
}

(There are enough clever solutions, so I felt the need to post a brute force one too.)

Sample run:

bash-4.1$ for i in {0..10}; do echo -n $i\ ; awk grade.awk <<< $i; done
0 Failed
1 Failed
2 Failed
3 Summer School
4 Summer School
5 Summer School
6 Summer School
7 Approved
8 Approved
9 Approved
10 Approved

marinus · Accepted Answer · 2013-07-06 08:34:30Z

APL

'Failed' 'Summer School' 'Approved'⌷⍨+/⎕≥0 3 7

Explanation:

⎕≥0 3 7: read input, see if it is bigger or equal to 0, 3 and 7 (this gives a vector of bits, i.e. if the input is 5 this gives 1 1 0)
+/: sum the vector (giving an index into the list)
⌷⍨: select the corresponding string from the list

Alpesh Darji · Accepted Answer · 2013-08-02 21:17:00Z

Using Javascript, Thanks to @Bakuriu

function decision(g) {
    var d = ["Approved","Summer School","Failed"];
    return d[(g<7)+(g<3)]
} 




console.log(decision(2)); ==> Failed
console.log(decision(5)); ==> Summer School
console.log(decision(9)); ==> Approved
console.log(decision(1)); ==> Failed
console.log(decision(4)); ==> Summer School

manatwork · Accepted Answer · 2013-07-22 06:21:30Z

-3

Java

public static String getFeedback(int grad) {
    String str = grad>=7? "Approved" : grad>=3 ?  "Summer School" : grad<3 ? "Failed"  : "";
    return str;
}

edited Jul 22 '13 at 6:21

manatwork

17.9k4 gold badges39 silver badges73 bronze badges

answered Jul 5 '13 at 12:24

imtiyaz

1

6

\$\begingroup\$ 1) That in not a program, just a snippet. At least post the whole method. 2) There are 3 ternary operators while only 1 is allowed. \$\endgroup\$ – manatwork Jul 5 '13 at 12:36

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Write a program with one & only if statement that [closed]

Challenge: You Are The Teacher

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