为什么我的 if...in 语句在 python 中不起作用？

Question

this program takes 3 lists of numbers, and compares A and B to the list n. if a term from A is in n, the happiness increases. if a term from B is in n, the happiness decreases. However, when I am doing these calculations, the if... in statement to check if a term from A/B is in n doesn't work - I have done print(happy) after each one to check, and I get no result

A = []
B = []
n = []
happy = 0
lengthn, lengthAB = input("").split()
for i in lengthn:
    numbers = input("")
newNumbers = numbers.split()
n.append(newNumbers)
for i in lengthAB:
    numbers = input("")
ANumbers = numbers.split()
A.append(ANumbers)
for i in lengthAB:
    numbers = input("")
BNumbers = numbers.split()
B.append(BNumbers)

long = int(lengthAB)
for i in range(long):
    j = int(i)
    if A[j - 1] in n:
        happy = happy + 1
        print(happy)
    if B[j - 1] in n:
        happy = happy - 1
        print(happy)
    i = i + 1

print(happy)

Thank you so much for the help!!

Answer 1

You appended a list to n , not each element of that list. You can write

n.extend(newNumbers)

instead.

You could just write n = newNumbers.split() , but as pointed out in a comment, you probably have an indentation error:

for i in lengthn:
    numbers = input("")
    newNumbers = numbers.split()
    n.extend(newNumbers)

Or, you don't need split at all:

for i in lengthn:
    number = int(input(""))
    n.append(number)

At some point, you probably mean to convert the string inputs to integers; may as well do that immediately after reading the string. (I'm declaring various techniques for handling conversion errors beyond the scope of this answer.)

Answer 2

Contrary to what you seem to expect the variables: lengthn, lengthAB are strings

The for -loop

for i in lengthn:
    numbers = input("")

iterates over the characters in the string lengthn. If lengthn='12' it will ask to provide input twice.

If lengthAB is '13' for example you will get 2 numbers in your list BNumbers but later on you try to test 13 values because int('13') is 13.

Answer 3

 for i in lengthn:
     numbers = input("")

so the numbers you are getting are the form of string it's will iterate on string rather then a number.

Answer 4

You should look for beeter python book. Based on desription I think this should look like this:

def happiness(A, B, n):
    return sum(x in n for x in A) - sum(x in n for x in B)

def get_data(prompt=""):
    return [int(x) for x in input(prompt).split()]

print(happiness(get_data(), get_data(), get_data()))

https://ideone.com/Q2MZCo