data.py

'''
This function takes two arguments,
data1 and data2, which contain
key-value pairs. All key-value
pairs within data1 are unique.
Similarly, all key-value pairs
within data2 are unique. However,
there may be key-value pairs (k, v1)
in data1 and (k, v2) in data2 with a
common key k. In this case, v1 and
v2 may be the same, or v1 and v2 may
be different.

This function should modify only
data1 and return a (possibly empty)
dictionary as follows:
For every key-value pair (k, v2) in
data2, if no key-value pair with key
k exists in data1, then the pair
(k, v2) should be added to data1.
Otherwise, there is a unique pair
(k, v1) already in data1. If v1 and
v2 are different, the pair (k, v1)
should be removed from data1 and the
key-value pair (k, [v1, v2]) should
be added to the (initially empty)
dictionary to be returned.

In this implementation, data1 is a
dictionary and data2 is a list where
each key-value pair in data2 is also
a list [key, value] of length 2.
'''

def uniqueUpdate(data1, data2):
    # Initially empty dictionary
    dupKeys = {}

    # Examine every (k, v2) pair in data2
    for k, v2 in data2.items():
        # Search for a key-value pair
        # with key = k in data1
        # (no such pair found yet)
        kFound = False

        for [k1, v1] in data1:
            if k1 == k:
                # Found pair with key = k
                kFound = True
                # Remove (k, v1) from data1
                data1.remove([k, v1])
                # Add (k, [v1, v2])
                # to dictionary
                dupKeys[k] = [v1, v2]

        # After the loop, check if
        # k was not found
        if not kFound:
            # Add (k, v2) to data1
            data1.append([k, v2])

    # After processing all (k, v2) in
    # data2, return the dictionary
    return dupKeys

'''
Visualize this function on an example:
https://tinyurl.com/dsaprac20
'''

## DO NOT MODIFY BELOW THIS LINE! ##
'''
This part of the code reads input in
the following format:

Line 1: A positive integer n1
representing the number of key value
pairs in data1
Lines 2 to n1+1: Two integers k v
per line representing the key and
value (these n1 key value pairs are
added to data1)
Line n1+2: A positive integer n2
representing the number of key value
pairs in data2
Lines n1+3 to n1+n2+2: Two integers
k and v per line representing the
key and value (these n2 key value
pairs are added to data2)

This also prints the output in the
following format after calling the
uniqueUpdate function:

data1
data2 (should remain the same)
dup (the dictionary returned)
'''

import sys
if __name__ == '__main__':
    data1 = []
    n1 = int(input())
    for _ in range(n1):
        k, v = map(int, input().split())
        for [k1, v1] in data1:
            if k1 == k:
                sys.exit("Illegal: data1")
        data1.append([k, v])
    data2 = {}
    n2 = int(input())
    for _ in range(n2):
        k, v = map(int, input().split())
        if k in data2:
            sys.exit("Illegal: data2")            
        data2[k] = v
    dup = uniqueUpdate(data1, data2)
    print(data1)
    print(data2)
    print(dup)