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Commit 3acb1dd

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day9:python uniquechars
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‎README.md

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| Current Status| Stats |
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| :------------: | :----------: |
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| Total C++ Problems | 188 |
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| Total Python Problems | 13 |
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| Current Daily Streak| 8 |
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| Total Python Problems | 14 |
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| Current Daily Streak| 9 |
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| Last Streak | 06/20/2019 - 06/21/2019|
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| Current Streak | 06/23/2019 - 06/30/2019|
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| Current Streak | 06/23/2019 - 07/01/2019|
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</center>
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### Cracking the coding interview problems
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| Problem | Solution |
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| :------------ | :----------: |
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| Problem 1-1 : Edition 6: Write an algorithm to determine whether a string has unique characters or not. Can we do it without using additional data structures? | [1-1-hasUniqueChars.cpp](cracking_the_coding_interview_problems/1-1-hasUniqueChars.cpp)|
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| Problem 1-1 : Edition 6: Write an algorithm to determine whether a string has unique characters or not. Can we do it without using additional data structures? | [1-1-hasUniqueChars.cpp](cracking_the_coding_interview_problems/1-1-hasUniqueChars.cpp), [1-1-hasUniqueChars.py](cracking_the_coding_interview_problems/1-1-hasUniqueChars.py)|
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| Problem 1-2 : Edition 5: Reverse a string when you are a pass a null terminated C string.|[1-2-edi5-reverseString.cpp ](cracking_the_coding_interview_problems/1-2-edi5-reverseString.cpp)|
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| Problem 1-2 : Edition 6: Given two strings, determine if one is permutation of other.|[1-2-perm-strings.cpp](cracking_the_coding_interview_problems/1-2-perm-strings.cpp)|
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| Problem 1-3 : Edition 5: Write an algorithm to remove duplicate chars from a string.|[1-3-edi5-removeDuplicates.cpp](cracking_the_coding_interview_problems/1-3-edi5-removeDuplicates.cpp)|
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"""
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Cracking the coding interview, edition 6
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Problem 1.1
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Write an algorithm to determine whether a string has unique characters or not
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Can we do it without using additional data structures?
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"""
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def is_unique(string):
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""" Checks if string has unique characters.
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Args:
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string: the string which needs to be checked for unique characters.
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This string only contains a-z lowercase (26 chars).
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'check' is 32-bit integer, 1 bit per alphabet.
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Returns:
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True if string has unique characters False otherwise
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"""
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check = 0
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for char in string:
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c = ord(char) - ord('a')
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if check & (1 << c) :
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return False
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check |= (1 << c)
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return True
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def is_unique2(string):
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""" Checks if string has unique characters
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Args:
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string: ASCII string which needs to be checked for unique characters
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Returns:
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True if string has unique characters False otherwise.
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"""
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check = [0 for _ in range(8)]
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for char in string:
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v = ord(char)
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# find int bucket which will represent this char
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idx = int(v / 32)
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# find the bit in this int bucket which will represent this char
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shift = v % 32
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if check[idx] & (1 << shift):
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return False
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check[idx] |= (1 << shift)
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return True
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if __name__ == "__main__":
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str1 = "hello"
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print(F"'{str1}' has unique characters? :", is_unique(str1))
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str2 = "norepat"
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print(F"'{str2}' has unique characters? :", is_unique2(str2))

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