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| /** | |
| * Definition for singly-linked list. | |
| * struct ListNode { | |
| * int val; | |
| * struct ListNode *next; | |
| * }; | |
| */ | |
| struct ListNode *detectCycle(struct ListNode *head) { | |
| static struct ListNode *Max_cycle_size_index = NULL; | |
| static struct ListNode *list_begin = NULL ; | |
| static struct ListNode *rabbit = NULL; | |
| if( list_begin == NULL ) | |
| { | |
| rabbit = head; | |
| list_begin = head; | |
| } | |
| if( Max_cycle_size_index == NULL ) | |
| { | |
| if( rabbit && rabbit->next && rabbit->next->next ) | |
| { | |
| head = head->next; | |
| rabbit = rabbit->next->next; | |
| if( head == rabbit ) | |
| { | |
| Max_cycle_size_index = rabbit ; | |
| return detectCycle( list_begin ); | |
| } | |
| return detectCycle( head ); | |
| } | |
| Max_cycle_size_index = NULL; | |
| list_begin = NULL; | |
| rabbit = NULL; | |
| return NULL; | |
| } | |
| else | |
| { | |
| if( rabbit == head ) | |
| { | |
| Max_cycle_size_index = NULL; | |
| list_begin = NULL; | |
| rabbit = NULL; | |
| return head; | |
| } | |
| head = head->next; | |
| rabbit = rabbit->next; | |
| return detectCycle( head ); | |
| } | |
| } |
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