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CycleDetection.cpp
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CycleDetection.cpp
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#include <bits/stdc++.h>
using namespace std;
class SinglyLinkedListNode {
public:
int data;
SinglyLinkedListNode *next;
SinglyLinkedListNode(int node_data) {
this->data = node_data;
this->next = nullptr;
}
};
class SinglyLinkedList {
public:
SinglyLinkedListNode *head;
SinglyLinkedListNode *tail;
SinglyLinkedList() {
this->head = nullptr;
this->tail = nullptr;
}
void insert_node(int node_data) {
SinglyLinkedListNode* node = new SinglyLinkedListNode(node_data);
if (!this->head) {
this->head = node;
} else {
this->tail->next = node;
}
this->tail = node;
}
};
void print_singly_linked_list(SinglyLinkedListNode* node, string sep, ofstream& fout) {
while (node) {
fout << node->data;
node = node->next;
if (node) {
fout << sep;
}
}
}
void free_singly_linked_list(SinglyLinkedListNode* node) {
while (node) {
SinglyLinkedListNode* temp = node;
node = node->next;
free(temp);
}
}
// Complete the has_cycle function below.
/*
* For your reference:
*
* SinglyLinkedListNode {
* int data;
* SinglyLinkedListNode* next;
* };
*
*/
bool has_cycle(SinglyLinkedListNode* head) {
SinglyLinkedListNode * pt1 = head;
SinglyLinkedListNode * pt2 = head;
while (pt1 != NULL && pt2 != NULL && pt2->next != NULL) {
pt1 = pt1->next;
pt2 = pt2->next->next;
if(pt1 == pt2) return true;
}
return false;
}
int main()
{
ofstream fout(getenv("OUTPUT_PATH"));
int tests;
cin >> tests;
cin.ignore(numeric_limits<streamsize>::max(), '\n');
for (int tests_itr = 0; tests_itr < tests; tests_itr++) {
int index;
cin >> index;
cin.ignore(numeric_limits<streamsize>::max(), '\n');
SinglyLinkedList* llist = new SinglyLinkedList();
int llist_count;
cin >> llist_count;
cin.ignore(numeric_limits<streamsize>::max(), '\n');
for (int i = 0; i < llist_count; i++) {
int llist_item;
cin >> llist_item;
cin.ignore(numeric_limits<streamsize>::max(), '\n');
llist->insert_node(llist_item);
}
SinglyLinkedListNode* extra = new SinglyLinkedListNode(-1);
SinglyLinkedListNode* temp = llist->head;
for (int i = 0; i < llist_count; i++) {
if (i == index) {
extra = temp;
}
if (i != llist_count-1) {
temp = temp->next;
}
}
temp->next = extra;
bool result = has_cycle(llist->head);
fout << result << "\n";
}
fout.close();
return 0;
}