206。Reverse Linked List

/*

Reverse a singly linked list.

*/

//解法一  21%  3ms

/**

 * Definition for singly-linked list.

 * struct ListNode {

 *     int val;

 *     struct ListNode *next;

 * };

 */

//思路：先创建iintnt 一个数组，查找一共有多少元素，然后放进数组中，利用数组倒转，然后再重新放到单链表中

struct ListNode* reverseList(struct ListNode* head) {

    struct ListNode* p,*q;

    int i=0,j,temp,count=0;

    int* nums;

    p = head;

    while(p)

    {

        p = p->next;

        count++;

    }

    nums = (int*)malloc(count*sizeof(int*));

    p = head;

    while(p)

    {

        nums[i] = p->val;

        p = p->next;

        i++;

    }

    

    for(i=0,j=count-1;i<count/2;i++,j--)

    {

        temp = nums[i];

        nums[i] = nums[j];

        nums[j] = temp;

    }

    

    p = head;

    i = 0;

    while(p)

    {

        p->val = nums[i];

        p = p->next;

        i++;

    }

    return head;

}