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December 7, 2023 17:04
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Classic Secret Santa Problem in 4 lines. Guarantees mathematically that no one will give to themselves and no two will give to each other.
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function secretSanta(...names) { | |
const randomized = [...names].sort(() => Math.random() - Math.random()); | |
const derrangement = [...randomized] | |
derrangement.unshift(derrangement.pop()) // shifting ensures a derrangement of the randomized list | |
return Object.fromEntries(randomized.map((name, idx) => [name, derrangement[idx]])) | |
} | |
secretSanta('Alice', 'Bob', 'Carter', 'David', 'Emily') | |
// { Carter: 'Emily', Bob: 'Carter', David: 'Bob', Alice: 'David', Emily: 'Alice' } |
You can also do all this as a one-liner, but it is much less readable:
const secretSanta =
(...names) => Object.fromEntries(
[...names].sort(() => Math.random() - 0.5)
.map((giver, idx, getters) => [giver, getters[(idx + 1) % getters.length]])
)
As a party trick, here is that same function minimized (under 100 bytes - it's 94, even room to add a let
at the front and still be under):
s=(...n)=>Object.fromEntries(n.sort(_=>Math.random()-.5).map((x,i,a)=>[x,a[(i+1)%a.length]]))
Unrelated
FizzBuzz in 39 bytes:
f=n=>(n%3?'':'Fizz')+(n%5?'':'Buzz')||n
isPalindrome in 46 bytes:
p=s=>[...s].every((c,i)=>c==s[(s.length-i)-1])
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For explanation of the math behind how this works: https://www.youtube.com/watch?v=5kC5k5QBqcc