# Python Set | Check whether a given string is Heterogram or not

• Difficulty Level : Easy
• Last Updated : 28 Dec, 2017

Given a string S of lower case characters. The task is to check whether a the given string is Heterogram or not. A heterogram is a word, phrase, or sentence in which no letter of the alphabet occurs more than once.

Examples:

```Input : S = "the big dwarf only jumps"
Output : Yes
Each alphabet in the string S is occurred
only once.

Input : S = "geeksforgeeks"
Output : No
Since alphabet 'g', 'e', 'k', 's' occurred
more than once.
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

We have existing solution for this problem please refer Check whether a given string is Heterogram or not link. We can solve this problem quickly in python using Set data structure. Approach is very simple,

1. To check sentence is heterogram or not we only concern about alphabets not any other character, so we separate out list of all alphabets present in sentence.
2. Convert list of alphabets into set because set contains unique values, if length of set is equal to number of alphabets that means each alphabet occured once then sentence is heterogram, otherwise not.
 `# Function to Check whether a given string is Heterogram or not `` ` `def` `heterogram(``input``):`` ` `     ``# separate out list of alphabets using list comprehension``     ``# ord function returns ascii value of character``     ``alphabets ``=` `[ ch ``for` `ch ``in` `input` `if` `( ``ord``(ch) >``=` `ord``(``'a'``) ``and` `ord``(ch) <``=` `ord``(``'z'``) )]`` ` `     ``# convert list of alphabets into set and ``     ``# compare lengths``     ``if` `len``(``set``(alphabets))``=``=``len``(alphabets):``         ``print` `(``'Yes'``)``     ``else``:``         ``print` `(``'No'``)`` ` `# Driver program``if` `__name__ ``=``=` `"__main__"``:``    ``input` `=` `'the big dwarf only jumps'``    ``heterogram(``input``)`

Output:

```Yes
```
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