Python program to check if a string contains all unique characters
To implement an algorithm to determine if a string contains all unique characters.
Examples:
Input : s = “abcd”
Output: True
“abcd” doesn’t contain any duplicates. Hence the output is True.Input : s = “abbd”
Output: False
“abbd” contains duplicates. Hence the output is False.
One solution is to create an array of boolean values, where the flag at the index i indicates whether character i in the alphabet is contained in the string. The second time you see this character you can immediately return false.
You can also return false if the string length exceeds the number of unique characters in the alphabet.
def isUniqueChars(st): # String length cannot be more than # 256. if len(st) > 256: return False # Initialize occurrences of all characters char_set = [False] * 128 # For every character, check if it exists # in char_set for i in range(0, len(st)): # Find ASCII value and check if it # exists in set. val = ord(st[i]) if char_set[val]: return False char_set[val] = True return True # driver code st = "abcd"print(isUniqueChars(st)) |
Output:
True