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Tips and Tricks for Strings

Common operations​

Sort a string alphabetically​

def sort_string(a)
    return ''.join(sorted(a))

Miscellaneous​

Count the characters in a string of unique characters​

A neat trick to count the characters in a string of unique characters is to use a 26-bit bitmask to indicate which lower case Latin characters are inside the string.

mask = 0
for c in word:
  mask |= (1 << (ord(c) - ord('a')))

To determine if two strings have common characters, perform & on the two bitmasks. If the result is non-zero (i.e., mask_a & mask_b > 0) then the two strings have common characters.