day 33: 200-number-of-islands, 141-linked-list-cycle

141-linked-list-cycle/driver.cpp

@@ -0,0 +1,16 @@
+#include "soln.hpp"
+
+int main()
+{
+	ListNode n5 = ListNode(5);
+	ListNode n4 = ListNode(4, &n5);
+	ListNode n3 = ListNode(3, &n4);
+	ListNode n2 = ListNode(2, &n3);
+	ListNode n1 = ListNode(1, &n2);
+	n5.next = &n3;
+	bool answer = true;
+
+	Solution soln;
+	cout << "Checked cycle correctly? " << soln.test(&n1, answer) << endl;
+	return 0;
+}

141-linked-list-cycle/soln.cpp

@@ -0,0 +1,19 @@
+#include "soln.hpp"
+
+bool Solution::hasCycle(ListNode *head)
+{
+	ListNode *slow = head, *fast = head;
+	while (fast && fast->next)
+	{
+		slow = slow->next;
+		fast = fast->next->next;
+		if (slow == fast)
+			return true;
+	}
+	return false;
+}
+
+bool Solution::test(ListNode *head, bool answer)
+{
+	return hasCycle(head) == answer;
+}

141-linked-list-cycle/soln.hpp

@@ -0,0 +1,18 @@
+#include <bits/stdc++.h>
+using namespace std;
+/* Singly linked list*/
+struct ListNode
+{
+	int val;
+	ListNode *next;
+	ListNode() : val(0), next(nullptr) {}
+	ListNode(int x) : val(x), next(nullptr) {}
+	ListNode(int x, ListNode *next) : val(x), next(next) {}
+};
+
+class Solution
+{
+public:
+	bool hasCycle(ListNode *head);
+	bool test(ListNode *head, bool answer);
+};