Suppose we have one equation in this form: a + b = c, now any one of the terms of a, b or c is missing. We have to find the missing one.
So, if the input is like ? + 4 = 9, then the output will be 5
To solve this, we will follow these steps −
delete all blank spaces from the string and change (+ and = to comma ',')
elements := a list of elements by splitting the string separated by comma
idx := 0
for i in range 0 to size of elements, do
if elements[i] is not numeric, then
idx := i
come out from the loop
if last element is missing, then
return first element + second element
otherwise when second element is missing, then
return last element - first element
otherwise when first element is missing, then
return last element - second element
Example
Let us see the following implementation to get better understanding −
def find_missing(string):
string = string.strip().replace(' ', '')
string = string.replace('=',',')
string = string.replace('+',',')
elements = string.split(',')
idx = 0
for i in range(len(elements)):
if not elements[i].isnumeric():
idx = i
break
if idx == 2:
return int(elements[0]) + int(elements[1])
elif idx == 1:
return int(elements[2]) - int(elements[0])
elif idx == 0:
return int(elements[2]) - int(elements[1])
print(find_missing('6 + 8 = ?'))
print(find_missing('? + 8 = 20'))
print(find_missing('5 + ? = 15'))Input
'6 + 8 = ?' '? + 8 = 20' '5 + ? = 15'
Output
14 12 10