you give alphanumeric string s alphanumeric string string consist lowercase English letter digitsyou find permutation string letter follow letter digit follow digit that adjacent character typereturn reformatte string return string impossible reformat string Example 1input s a0b1c2output 0a1b2cexplanation no adjacent character type 0a1b2c a0b1c2 0a1b2c 0c2a1b valid permutationsExample 2input s leetcodeoutput Explanation leetcode character separate digitsExample 3input s 1229857369output Explanation 1229857369 digit separate character Constraints1 slength 500s consist lowercase english letter andor digit