问在两个python字典之间的每个公共键中减去两个列表的最有效方法

EN

x={
    '1' : [1,2,3],
    '2' : [2,9]
}
y={
    '1' : [4,5],
    '3' : [8,9]
}

# Common key is '1' , so z is the list of the subtraction of elements of key '1'
>> expected_output = [-3, -2, -1, -4, -3, -2]
                   = [1-4,2-4,3-4, 1-5,2-5,3-5]

import random

x={}
y={}
num_same_keys = 100
num_diff_keys = 200

## Generating common keys with arbitrary number of elements
common_key = random.randint(0,10000)
for _ in range(num_same_keys) : 
    while common_key in x : common_key = random.randint(0,10000)
    x[common_key] = [ random.randint(0,1000) for _ in range(random.randint(1,10)) ]
    y[common_key] = [ random.randint(0,1000) for _ in range(random.randint(1,10)) ]

## Generating different keys with arbitrary number of elements
x_key = random.randint(0,10000)
y_key = random.randint(0,10000)
for _ in range(num_diff_keys) : 
    # Adding to x    
    while (x_key in x) and (x_key in y) : x_key = random.randint(0,10000)
    x[x_key] = [ random.randint(0,1000) for _ in range(random.randint(1,10)) ]
    # Adding to y
    while (y_key in x) and (y_key in y) : y_key = random.randint(0,10000)
    y[y_key] = [ random.randint(0,1000) for _ in range(random.randint(1,10)) ]