leetcode之Insertion Sort List

Sort a linked list using insertion sort.

此题较简单，就是练习链表增删查问题

class Solution {public:    ListNode *insertionSortList(ListNode *head) {        // IMPORTANT: Please reset any member data you declared, as        // the same Solution instance will be reused for each test case.        if(NULL == head || NULL==head->next) return head;        ListNode *p = head->next, *q, *trace,*pre, *curPre = head;        while(p){            trace = head;            pre = NULL;            q = p->next;            while(trace != p){                        //从头节点开始查找节点值是否有比当前节点p值大的                 if(trace->val > p->val){                    if(NULL == pre){                        curPre->next = p->next;                        p->next = head;                        head = p;                        break;                    }                    curPre->next = p->next;                    p->next = pre->next;                    pre->next = p;                    break;                }                                pre = trace;                trace = trace->next;            }            //如果p节点被插入到前面的节点中             if(trace != p){                p = q;            }            else{                curPre = p;                p=p->next;            }        }        return head;            }};