我在 python 中写的程序有什么问题？

Question

The question description is Write a program to get the input of key and value of the element in dictionary.

Display the key-value pair in the python dictionary format and find the length of the dictionary.

Test Case 1:

INPUT

3

23

33

43

32

33

34

OUTPUT

The dictionary is

{23: 32, 33: 33, 43: 34}

Length of dictionary is

3

My code is:

n = int(input())
di = dict()
for i in range(0, n):
  a = int(input())
  b = int(input())
  di[a] = b

print("The dictionary is")
print(di)
print("Length of dictionary is")
print(len(di))

The output I am getting for the same input given above is:

The dictionary is

{23: 33, 43: 32, 33: 34}

Length of dictionary is

3

What is my mistake?

Answer 1

It looks like the input provided is in the following order: i) size of the dictionary ii) the keys iii) the values

You seem to read it as key, value, key value...

Answer 2

The input provided is in the following order:

1. size of the dictionary
2. the keys
3. the values

So your code should look more like this:

# collecting length
n=int(input())

# creating lists for keys and values
keys_list = []
values_list = []

# collecting keys
for i in range(0,n):
  a=int(input())
  keys_list.append(a)

# collecting values
for i in range(0,n):
  a=int(input())
  values_list.append(a)

# creating dictionnary
di = dict(zip(keys_list, values_list)) 

# printing result
print("The dictionary is")
print(di)
print("Length of dictionary is")
print(len(di))

Like this, you're first collecting all the keys and putting them in a list, then you're collecting all the values and putting them in a list.
Finally, you're creating your dictionnary from these two lists.

Answer 3

Maybe simply this:

n = int(input('Input len of dict: '))

j = 0
l = []
while j != n * 2:
    l.append(input('input num: '))
    j += 1


di = {int(x): int(x[::-1]) for x in l[:3] if x[::-1] in l}
print(f"The dictionary is {di}\nLength of dictionary is {len(di)}")