Uiua, 19 bytes (SBCS)
Defines a function that takes the string and returns a string:
⊂@#♭⍥⍉⊙(↯2_3)=3⊸⧻↘1
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Explanation
⊂@#♭⍥⍉⊙(↯2_3)=3⊸⧻↘1 "#ABC" example input
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Uiua, 10 bytes (SBCS)
Counts all digit occurrences and checks the count array is all-equal (for which there is no short idiom in Uiua yet except for that deduplicate-length-equal-to-one and simila...
Uiua, 19 17 bytes (SBCS)
Takes argument as integer (decimal), returns lone ones count.
/+↧↧∩¬⊸∩⌟⬚0↻¯∩1⊥₂
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Explanation
Rotates binary representation left and right (negate...
Uiua, 38 bytes (SBCS)
Full program, prints diamond to STDOUT. Some nifty tricks turned out to be longer than some straightforward ways. Uses one leading whitespace even on the longest line to make...