chore(CPlusPlus): add fibonacci series (#365)

Co-authored-by: Ujjwal <75884061+UG-SEP@users.noreply.github.com>

algorithms/CPlusPlus/Maths/fibonacci-series.cpp

@@ -0,0 +1,69 @@
+#include <iostream>
+
+using namespace std;
+
+class Fibonacci 
+{
+    /**
+     *   The Fibonacci Sequence is the series of numbers:
+     *
+     *   0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ...
+     *
+     *   The next number is found by adding up the two numbers before it:, next number is the sum of previous two numbers
+     *   for example 0,
+     *   1, 1, 2, 3, 5, 8, 13, 21 etc. 
+     *   The first two numbers of fibonacci series are 0 and 1.
+     *   Time complexity: O(n)
+     * */
+public:
+    /*
+     *   Example 1: the number of elements is introduced by the user via command prompt.
+     */
+    void print_fibonacci_no_R() 
+    {
+        int num1 = 0, num2 = 1, num3, i, number;
+        cout << "Enter the number of elements: ";
+        cin >> number;
+        cout << num1 << " " << num2 << " "; //printing 0 and 1
+
+        for (i = 2; i < number; ++i) //loop starts from 2 because 0 and 1 are already printed
+        {
+            num3 = num1 + num2;
+            cout << num3 << " ";
+            num1 = num2;
+            num2 = num3;
+        }
+        cout << "\n\n"; //printing 0 and 1
+    }
+
+    /*
+     *   Example 2: the number of elements is introduced by the user via function input parameter.
+     */
+    void printFibonacci_R(int n) 
+    {
+        if (n > 2)
+        { // n finishes at 2 because 0 and 1 are already printed
+            if (n1 == 0) cout << n1 << " " << n2 << " "; //printing 0 and 1
+            n3 = n1 + n2;
+            n1 = n2;
+            n2 = n3;
+            cout << n3 << " ";
+            printFibonacci_R(n - 1);
+        }
+    }
+
+private:
+    int n1{0};
+    int n2{1};
+    int n3;
+
+};
+
+
+int main()
+{
+    Fibonacci f;
+    f.print_fibonacci_no_R();
+    f.printFibonacci_R(8);
+    return 0;
+}

algorithms/CPlusPlus/README.md

@@ -78,3 +78,4 @@
 1. [Kaprekar Number](Maths/Kaprekar-number.cpp)
 2. [Prime Number](Maths/prime-check.cpp)
 3. [Prime Sieve](Maths/prime-sieve.cpp)
+4. [Fibonacci Series](Maths/fibonaccci-series.cpp)