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Number of 1s in a binary string
Find the number of 1s in the given binary string. Example. If the input string is '1100101', the output is 4. If the input stri...

7 years 前

已解决

Return the first and last character of a string
Return the first and last character of a string, concatenated together. If there is only one character in the string, the functi...

7 years 前