搜狐一题面试题 链表的排序

今天一同学去参加搜狐的笔试，说是遇到了一题链表的排序题

一般采用merge sort ，只是链表的排序和数组的排序不太一样，毕竟你得把链表跑一边才知道他是怎样的

#include <stdio.h>#include <stdlib.h>struct node{    int data;    struct node* next;};struct node* Sort(node*a,node*b);struct node* MergeSort(node* head){    node* a = NULL;    node* b = NULL;    if(head == NULL||head->next == NULL)return head;struct node* fast;    struct node* slow;      slow = head;      fast = head->next;        while(fast != NULL)      {        fast = fast->next;        if( fast != NULL )        {            slow = slow->next;            fast = fast->next;        }    }      a = head;    b = slow->next;    slow->next = NULL;    a = MergeSort(a);    b = MergeSort(b);return Sort(a,b);}struct node* Sort(node*a,node*b){struct node* result;if(a==NULL)return b;if(b==NULL)return a;if(a->data <= b->data)    {        result = a;        result->next = Sort(a->next, b);    }    else      {        result = b;        result->next = Sort(a, b->next);    }    return result;}  void printList(struct node* node)  //打印链表{      while( node != NULL )      {          printf("%d  ", node->data);          node = node->next;      }  }  

自己写了一段很蠢的测试代码

int main()  { struct node* head = NULL;  struct node* a,*b;struct node* ans = NULL;  a =b= (struct node*)malloc(sizeof(struct node));a->data = 2;head = a;b=a;a = (struct node*)malloc(sizeof(struct node));a->data = 3;b ->next = a;b = a;a = (struct node*)malloc(sizeof(struct node));a->data = 15;b ->next = a;b = a;a = (struct node*)malloc(sizeof(struct node));a->data = 4;b ->next = a;b = a;b->next = NULL;    ans = MergeSort(head);    printf("Sorted Linked List is: \n");    printList(ans);//链表输出    return 0;  }