After the Spring Festival Gala, "Liu Qian's biggest career rival " Xiao Ni admitted his mistake backstage: "I'm sorry, Teacher Liu Qian!"
Many viewers were curious, what two cards did Xiao Ni have left in his hand? Yu Lei, the general director of the Spring Festival Gala, announced the secret: the last thing left in Xiao Ni's hand was "half a, half q"! Yu Lei imitated Xiao Ni's inner drama at that time "What should I do if I become wrong?" "Should I expose it to the national audience..."
And like Xiao Ni, there are many netizens who failed. Related discussions continue to this day. Many netizens pointed out that in fact, this magic is not only a magic, but also an mathematical problem.
What is the mystery behind this magic "miracle"? On February 11, the Peking University WeChat public account posted a message, and several Peking University students revealed the magic of the Spring Festival Gala.
Magic Steps
Steps1
Tear the 4 prepared playing cards into two equal parts
and stack them together
Steps2
Move the cards with the number of
[number of characters in the name] at the top of the deck
to the bottom of the deck
Steps3
Place the first three cards in the middle of the deck
and take out the top card
and put it aside
Steps 4
Take out a few cards on the top of the deck
Insert them into the middle of the deck
The number of cards selected here is
The southerners take 1 card, the northerner takes 2 cards
If you are not sure whether it is the southerner or the northerner, take 3 cards
steps 5
The boy throws away the top 1 card of the card pile
The girl throws away the top 2 cards of the card pile
steps 6
Execute "Witness the moment of miracles" "Loop
Every time you say a word
take out the top card of the deck and place it on the bottom of the deck
Steps 7
Perform the following operations?
Start from the top of the deck
Each time, first put the top card of the deck on the deck bottom
and throw away the top card of the deck
Repeat the above operation until there is only one card left
Check whether this card matches the card placed aside
If they match, the magic is successful
Magic Revealed
Step One
Step Two
At this point we can notice that no matter how many cards we move from the top of the pile to the bottom, the resulting poker pile number (from top to bottom) will only have the following results:
Observe the above possible cards Pile, we can find that the generated card piles have the following properties:
1. The order of the first four cards and the last four cards is exactly the same
2. The first four cards and the last four cards are a rotation of 1234 respectively
Step 3
From this step on, we only consider the fourth and eighth cards in the current deck, which are recorded as x, and the other cards are recorded as 0. Then based on the discussion in the previous step, we can get the current deck shape as:
000x000x
After placing the first three cards in the middle of the deck, no matter where these three cards are placed, the final deck will be:
x000000x
So, The card selected for matching will be x, and the other card paired with it (called the target card) will be at the bottom of the deck.
Step 4
After the previous step, the number of the deck is 000000x. Therefore, no matter how many cards from the top of the deck are selected and inserted into the deck in this round, it will not affect the position of the target card, and it will still be at the bottom of the deck.
Step five
At this time, the boy's card pile is: 00000x
The girl's card pile is: 0000x
Step six
It can be seen from the experiment that after step six, the following card pile will be obtained:
Boy's : 0000x0
girls : 00x00
step seven
It is not difficult to see that behind this magic is actually a mathematical problem, which is called the Joseph problem.
In this case, why did host Nigmaiti fail?
In steps 3 and 4, if done correctly, the bottom card in each host's hand remains unchanged, and this happens to be the card left after step 7.
However, when performing step 4, pay attention to Nigmaiti's hand movements:
It turns out that Nigamaiti did not put the two cards into the middle position as required, which led to the failure of his final match. .
However, even though the top academics from Peking University wrote in such detail, many netizens, including the editor, still said: I still can’t understand...
Do you understand?
Comprehensive from Red Star News, CCTV News, China News Network, Peking University, Hubei Daily, public information, etc.
Source: Daily Economic News
