wehub-resource-sync
dde272c4b8
i18n - Build Validation / Validate i18n Builds (24) (push) Has been cancelled
CI - Node.js / Lint (24) (push) Has been cancelled
CI - Node.js / Build (24) (push) Has been cancelled
CI - Node.js / Test (24) (push) Has been cancelled
CI - Node.js / Test - Upcoming Changes (24) (push) Has been cancelled
CI - Node.js / Test - i18n (italian, 24) (push) Has been cancelled
CI - Node.js / Test - i18n (portuguese, 24) (push) Has been cancelled
CD - Docker - GHCR Images / Build and Push Images (push) Has been cancelled
82 lines
1.7 KiB
Markdown
82 lines
1.7 KiB
Markdown
---
|
|
id: 69162d64f96574d9bb629f01
|
|
title: "Challenge 116: Permutation Count"
|
|
challengeType: 29
|
|
dashedName: challenge-116
|
|
---
|
|
|
|
# --description--
|
|
|
|
Given a string, return the number of distinct permutations that can be formed from its characters.
|
|
|
|
- A permutation is any reordering of the characters in the string.
|
|
- Do not count duplicate permutations.
|
|
- If the string contains repeated characters, repeated arrangements should only be counted once.
|
|
- The string will contain only letters (`A-Z`, `a-z`).
|
|
|
|
For example, given `"abb"`, return `3` because there's three unique ways to arrange the letters: `"abb"`, `"bab"`, and `"bba"`.
|
|
|
|
# --hints--
|
|
|
|
`count_permutations("abb")` should return `3`.
|
|
|
|
```js
|
|
({test: () => { runPython(`
|
|
from unittest import TestCase
|
|
TestCase().assertEqual(count_permutations("abb"), 3)`)
|
|
}})
|
|
```
|
|
|
|
`count_permutations("abc")` should return `6`.
|
|
|
|
```js
|
|
({test: () => { runPython(`
|
|
from unittest import TestCase
|
|
TestCase().assertEqual(count_permutations("abc"), 6)`)
|
|
}})
|
|
```
|
|
|
|
`count_permutations("racecar")` should return `630`.
|
|
|
|
```js
|
|
({test: () => { runPython(`
|
|
from unittest import TestCase
|
|
TestCase().assertEqual(count_permutations("racecar"), 630)`)
|
|
}})
|
|
```
|
|
|
|
`count_permutations("freecodecamp")` should return `39916800`.
|
|
|
|
```js
|
|
({test: () => { runPython(`
|
|
from unittest import TestCase
|
|
TestCase().assertEqual(count_permutations("freecodecamp"), 39916800)`)
|
|
}})
|
|
```
|
|
|
|
# --seed--
|
|
|
|
## --seed-contents--
|
|
|
|
```py
|
|
def count_permutations(s):
|
|
|
|
return s
|
|
```
|
|
|
|
# --solutions--
|
|
|
|
```py
|
|
from math import factorial
|
|
from collections import Counter
|
|
def count_permutations(s):
|
|
freq = Counter(s)
|
|
n = len(s)
|
|
|
|
result = factorial(n)
|
|
for count in freq.values():
|
|
result //= factorial(count)
|
|
|
|
return result
|
|
```
|