题目描述 输入一个链表,输出该链表中倒数第k个结点。
Java AC代码:
/*
public class ListNode {
int val;
ListNode next = null;
ListNode(int val) {
this.val = val;
}
}*/
public class Solution {
public ListNode FindKthToTail(ListNode head,int k) {
ListNode p = head;
int len = 0;
if (k < 0) {
System.out.println("k不可以为负数");
return null;
}
if (head == null) {
System.out.println("单链表为空");
return null;
}
while(p != null){
len++;
p = p.next;
}
if ( k > len){
System.out.print("单链表太短");
return null;
}else{
k = len - k ;
while(k > 0){
head = head.next;
k--;
}
return head;
}
}
}
C++ AC代码
struct ListNode {
int val;
struct ListNode *next;
ListNode(int x) :
val(x), next(NULL) {
}
};
class Solution {
public:
ListNode* FindKthToTail(ListNode* pListHead, unsigned int k) {
if (k <= 0 || pListHead == NULL){
return NULL;
}
ListNode* p1 = pListHead;
ListNode* p2 = pListHead;
for(int i = 0 ; i != k ; i++){
if(p1 == NULL){
return NULL;
}else{
p1 = p1->next;
}
}
while(p1){
p1 = p1->next;
p2 = p2->next;
}
return p2;
}
};