Given an input string s = 'abcabc'. The character 'a' first occurs at position 0 and recurs at position 3. The character 'b' first occurs at position 1 and recurs at position 4. The character 'c' first occurs at position 2 and recurs at position 5. The character 'a' is the first repeated character in the input string. The output is 'a'. Given an input string s = 'abc'. The character 'a' only occurs at position 0. The character 'b' only occurs at position 1. The character 'c' only occurs at position 2. The output is None. Given an input string s = '12323'. The character '1' only occurs at position 0. The character '2' first occurs at position 1 and recurs at position 3. The character '3' first occurs at position 2 and recurs at position 4. The character '2' is the first repeated character in the input string. The output is '2'.
['abcabc'] ['abc'] ['12323']
'a' None '2'