c++ algorithms

Ronak_program/Floyd.cpp

@@ -0,0 +1,77 @@
+// Floyd's algorithm to detect cyle in linked list
+// c++ codecl
+
+#include <bits/stdc++.h>
+using namespace std;
+
+class Node
+{
+public:
+	int data;
+	Node *next;
+
+	Node(int data)
+	{
+		this->data = data;
+		next = NULL;
+	}
+};
+
+Node *head = NULL;
+class Linkedlist
+{
+public:
+	void insert(int value)
+	{
+		Node *newNode = new Node(value);
+		if (head == NULL)
+			head = newNode;
+		else
+		{
+			newNode->next = head;
+			head = newNode;
+		}
+	}
+
+	bool detectLoop()
+	{
+		Node *slowPointer = head,
+			 *fastPointer = head;
+
+		while (slowPointer != NULL && fastPointer != NULL && fastPointer->next != NULL)
+		{
+			slowPointer = slowPointer->next;
+			fastPointer = fastPointer->next->next;
+			if (slowPointer == fastPointer)
+				return 1;
+		}
+
+		return 0;
+	}
+};
+
+int main()
+{
+	// creating linked list
+	Linkedlist l1;
+	l1.insert(10);
+	l1.insert(20);
+	l1.insert(30);
+	l1.insert(40);
+	l1.insert(50);
+
+	// creating loop in linked list
+	Node *temp = head;
+	while (temp->next != NULL)
+		temp = temp->next;
+
+	temp->next = head;
+
+	// determining whether cycle is present or not
+	if (l1.detectLoop())
+		cout<<"Loop Found"<< endl;
+	else
+		cout<<"Loop does not exists"<< endl;
+
+	return 0;
+}

Ronak_program/Wilson.cpp

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+//Find Prime number using Wilson's theorem 
+//Chect whether number is prime or not.
+
+#include <iomanip>
+#include <iostream>
+
+int factorial_mod(int n, int p) {
+    int f = 1;
+    for (; n > 0 && f != 0; --n)
+        f = (f * n) % p;
+    return f;
+}
+
+bool is_prime(int p) {
+    return p > 1 && factorial_mod(p - 1, p) == p - 1;
+}
+
+int main() {
+    std::cout << "  n | prime?\n------------\n";
+    std::cout << std::boolalpha;
+    for (int p : {2, 3, 9, 15, 29, 37, 47, 57, 67, 77, 87, 97, 237, 409, 659})
+        std::cout << std::setw(3) << p << " | " << is_prime(p) << '\n';
+
+    std::cout << "\nFirst 120 primes by Wilson's theorem:\n";
+    int n = 0, p = 1;
+    for (; n < 120; ++p) {
+        if (is_prime(p))
+            std::cout << std::setw(3) << p << (++n % 20 == 0 ? '\n' : ' ');
+    }
+
+    std::cout << "\n1000th through 1015th primes:\n";
+    for (int i = 0; n < 1015; ++p) {
+        if (is_prime(p)) {
+            if (++n >= 1000)
+                std::cout << std::setw(4) << p << (++i % 16 == 0 ? '\n' : ' ');
+        }
+    }
+}