Question

w0='code'
w1='door'
mismatches=0

for letter in w0:
if w0.count(letter)!= w1.count(letter):
mismatches += w1.count(letter)
print(mismatches)

Answer is 2 but how do we find this answer by Python code

Answer 1

w0 = 'code'
w1 = 'door'

go through each letter in w0
letter 'c'
    count of 'c' in w0 is 1, count of 'c' in w1 is 0
    counts are not equal. so, add count of 'c' in w1 to mismatch
    mismatch += 0
    so, mismatch is 0
letter 'o'
    count of 'o' in w0 is 1, count of 'o' in w1 is 2
    counts are not equal. so, add count of 'c' in w1 to mismatch
    mismatch += 2
    so, mismatch is 2
letter 'd'
    count of 'd' in w0 is 1, count of 'd' in w1 is 1
    counts are equal. so, we don't need to add anything to mismatch
letter 'e'
    count of 'e' in w0 is 1, count of 'e' in w1 is 0
    counts are not equal. so, add count of 'e' in w1 to mismatch
    mismatch += 0
    so, mismatch is 2

so, final value of mismatch is 2.
Answer: 2

Python code:
-------------
w0 = 'code'
w1 = 'door'
mismatches = 0

for letter in w0:
    if w0.count(letter) != w1.count(letter):
        mismatches += w1.count(letter)
print(mismatches)