快慢指针
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* findKthToTail(ListNode* p, int k) {
ListNode* fast = p,*slow = p;//设置快慢指针
int len = 0;
while(p){//求链表长度
len++;
p = p->next;
}
if(len<k) return NULL;
while(k&&fast!=NULL){//先移动快空指针
fast = fast->next;
k--;
}
while(fast!=NULL){//移动慢指针
fast = fast->next;
slow = slow->next;
}
return slow;
}
};
大二的时候在力扣上做过这道题