Linked List Cycle

Linked List Cycle

Problem:

Given A linked list, determine if it has a cycle in it.

Ideas:

Fast pointer, slow pointer method

My Code:

 Public classSolution { Public Booleanhascycle (ListNode head) {if(Head = =NULL|| Head.next = =NULL)            return false ; ListNode One=Head; ListNode=Head.next.next;  while(One! =NULL&& both! =NULL)        {            if(One = =Both )return true ; One=One.next; if(Two.next = =NULL)                 Break ; both=Two.next.next; }        return false ; }}

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Others code:

 Public classSolution { Public Booleanhascycle (ListNode head) {if(Head = =NULL) {            return false; } ListNode Fast= Head, slow =Head;  Do {            if(Fast.next = =NULL|| Fast.next.next = =NULL) {                return false; } Fast=Fast.next.next; Slow=Slow.next; }  while(Fast! =slow); return true; }}

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The Learning Place:

• If there is no cycle, the fast pointer must go to NULL first
• The magic of doing while can be judged.

Linked List Cycle