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Challenge 30: Unique Characters

curriculum/challenges/english/blocks/daily-coding-challenges-python/68af0687ef34c76c28ffa547.md

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--description--

Given a string, determine if all the characters in the string are unique.

  • Uppercase and lowercase letters should be considered different characters.

--hints--

all_unique("abc") should return True.

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(all_unique("abc"), True)`)
}})

all_unique("aA") should return True.

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(all_unique("aA"), True)`)
}})

all_unique("QwErTy123!@") should return True.

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(all_unique("QwErTy123!@"), True)`)
}})

all_unique("~!@#$%^&*()_+") should return True.

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(all_unique("~!@#$%^&*()_+"), True)`)
}})

all_unique("hello") should return False.

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(all_unique("hello"), False)`)
}})

all_unique("freeCodeCamp") should return False.

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(all_unique("freeCodeCamp"), False)`)
}})

all_unique("!@#*$%^&*()aA") should return False.

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(all_unique("!@#*$%^&*()aA"), False)`)
}})

--seed--

--seed-contents--

py
def all_unique(s):

    return s

--solutions--

py
def all_unique(s):
    seen = set()
    for ch in s:
        if ch in seen:
            return False
        seen.add(ch)
    return True