leetcode:Reverse Nodes in k-Group(以k为循环节反转链表)【面试算法题】
题目:Givenalinkedlist,reversethenodesofalinkedlistkatatimeandreturnitsmodifiedlist.Ifthenumberofnodesisnotamultipleofkthenleft-outnodesintheendshouldremainasitis.Youmaynotalterthevaluesinthenodes,onlyno