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// 141. Linked List Cycle
#include "leetcode.h"
/*
* given the 'head' of a linked list, determine if the linked list has a cycle
* in it. there is a cycle in a linked list if there is some node in the list
* that can be reached again by continuously following the 'next' pointer.
* internally, 'pos' is used to denote the index of the node that tail's 'next'
* pointer is connected to. note that 'pos' is not passed as a parameter. return
* true if there is a cycle in the linked list. otherwise return false.
*/
struct ListNode {
int val;
struct ListNode *next;
};
struct hash_entry {
int id;
char name[10];
UT_hash_handle hh;
};
bool hasCycle(struct ListNode *head) {
struct ListNode *tmp = head;
struct hash_entry *s, *users = NULL;
while (tmp) {
long user_id = tmp;
HASH_FIND_INT(users, &user_id, s);
if (!s) {
s = malloc(sizeof(*s));
s->id = tmp;
HASH_ADD_INT(users, id, s);
} else
return true;
tmp = tmp->next;
}
return false;
}
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