-- Code function f(s,i)j=i or 0return#s>j and s..f(s:reverse(),j+1)or''end -- Test cases print(f("Hello!")) print(f("a")) print(f("abcd")) print(f("OK!")) print(f("4815162342")) print(f("PPCG")) print(f("42"))
Standard input is empty
Hello!!olleHHello!!olleHHello!!olleH a abcddcbaabcddcba OK!!KOOK! 4815162342243261518448151623422432615184481516234224326151844815162342243261518448151623422432615184 PPCGGCPPPPCGGCPP 4224