`/**
- Definition for singly-linked list.
- struct ListNode {
-
int val;
-
struct ListNode *next;
- };
*/
struct ListNode* reverseList(struct ListNode* head){
struct ListNode* newhead = NULL,tmp;
while(head){
/ tmp = head->next;
head->next = newhead;
newhead = head;
head = tmp;//保存head->next,接下来将1独立拿出来,head->next = NULL;*/
tmp = head;
head = head->next;
tmp->next = newhead;
newhead = tmp;
}
return newhead;
}`
如果tmp = head->next和tmp = head区别在于前者保存了下一个结点,而后者是暂存当前结点,所以后者不能上来就head->next = newhead,会丢失后面下一个结点。
两个写法的newhead含义恰恰相反,前者newhead是暂存当前结点,后者由于头节点已经向后移动了,导致newhead暂存的是下一结点。