python script help

I’m trying to solve this puzzle my sister’s teacher gave to her. It’s to get 24 out of 4 numbers 20, 10, 11 and 4.
So I wrote this program, and here’s the code and the result:

a=0
b=1
c=2
d=3
x = 0
integer = ["20", "10", "11", "4"]
operation = ["*", "/", "+", "-"]
while x != 24:
     
    
    formula = integer[a]+operation[a]+integer[b]+operation[b]+integer[c]+operation[c]+integer[d]
    x = formula 
    if  a <= 3:
        a += 1
    elif a == 3:
        a -= 1
    if  b <= 3:
        b += 1
    elif b == 3:
        b -= 1    
    if  c <= 3:
        c += 1
    elif c == 3:
        c -= 1
    if  d <= 3:
        d += 1
    elif d == 3:
        d -= 1            
            
    
        
    print formula
if x == 24:
    print formula    
    
    

Result:

[email protected]:~$ python zainabhomework.py 
20*10/11+4
Traceback (most recent call last):
  File "zainabhomework.py", line 11, in <module>
    formula = integer[a]+operation[a]+integer[b]+operation[b]+integer[c]+operation[c]+integer[d]
IndexError: list index out of range

thanks in advance

Change your ‘<=’ to just strictly less than, i.e, ‘<’:


if a &lt; 3:
     a +=  1
elif a == 3:
     a -= 1

Continue this change for all of them (it still won’t work like you want, but it’ll get you past that error).

thanks, but now i get an endless repeat of the same thing…any help on how i can fix that?