判斷連結串列是否有環
阿新 • • 發佈:2019-01-27
/**
* Definition of ListNode
* class ListNode {
* public:
* int val;
* ListNode *next;
* ListNode(int val) {
* this->val = val;
* this->next = NULL;
* }
* }
*/
class Solution {
public:
/**
* @param head: The first node of linked list.
* @return: True if it has a cycle, or false
*/
bool hasCycle(ListNode *head) {
// write your code here
ListNode *onestep;
ListNode *twosteps;
if (!head)
return false;
onestep = head->next;
if (head->next)
twosteps = head->next->next;
else
return false;
while (onestep && twosteps) {
if (onestep == twosteps)
return true;
onestep = onestep->next;
if (twosteps->next) {
twosteps = twosteps->next->next;
} else {
return false;
}
}
return false;
}
};
* Definition of ListNode
* class ListNode {
* public:
* int val;
* ListNode *next;
* ListNode(int val) {
* this->val = val;
* this->next = NULL;
* }
* }
*/
class Solution {
public:
/**
* @param head: The first node of linked list.
* @return: True if it has a cycle, or false
*/
bool hasCycle(ListNode *head) {
// write your code here
ListNode *onestep;
ListNode *twosteps;
if (!head)
return false;
onestep = head->next;
if (head->next)
twosteps = head->next->next;
else
return false;
while (onestep && twosteps) {
if (onestep == twosteps)
return true;
onestep = onestep->next;
if (twosteps->next) {
twosteps = twosteps->next->next;
} else {
return false;
}
}
return false;
}
};