Easy understand Python solution
\n\nres = \'\'\nfor i in range(0, len(s), 2*k):\n    res += s[i:i+k][::-1]+s[i+k:i+2*k]\nreturn res\n
\n```\nres = \'\'\nfor i in range(0, len(s), 2*k):\n    res += s[i:i+k][::-1]+s[i+k:i+2*k]\nreturn res\n```
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