# Matching Cards in Two Decks

Python Puzzles

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If you shuffle two separate decks of cards, what is the probability of the same card appearing in the exact same position in the two separate decks?

Approximately 36% of the time the two decks will have zero matching cards in the same position; 64% of the time it will have at least one matching card. When I run the simulation 1 million times, the most matches I get is 9.

```import random
from collections import Counter
import matplotlib.pyplot as plt
loop = 1_000_000
result_total = []

# create a deck of cards
deck_of_cards1 = list(range(1,53))
deck_of_cards2 = list(range(1,53))

for _ in range(loop):

random.shuffle(deck_of_cards1)
random.shuffle(deck_of_cards2)
result = []

for d1, d2 in zip(deck_of_cards1, deck_of_cards2):
if d1 == d2:
result.append(1)
result_total.append(result.count(1))

result_total.sort()
keys = list(Counter(result_total).keys())
values = list(Counter(result_total).values())

values_pct = []
# determine percent
for x in values:
values_pct.append(x/loop)

#create a bar chart
plt.bar(keys,values_pct)
plt.ylabel("Percentage")
plt.xlabel("# of Card Matches")
plt.title("Probability")
plt.xticks(keys)
plt.show()
values_pct.sort(reverse=True)
print(values_pct)```