Fibonacci number Implementation in JS. Closes #1609

Fibonacci_Number/Fibonacci_Number.js

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+// Problem Statement(1): Find the nth Fibonacci number
+// (1.a) Using Recusrsion
+// (1.b) Using Dynamic Programming(DP)
+// Problem Statement(2): Print the Fibonacci series
+
+// 1.a Using Recusrion to find the nth fibonacci number
+const FibonacciNumberRec = num => {
+    if (num <= 1) return num;
+    return FibonacciNumberRec(num - 1) + FibonacciNumberRec(num - 2);
+};
+
+// 1.b Using DP to find the nth fibonacci number
+// fib[n] = fib[n - 1] + fib[n - 2]
+
+const FibonacciNumberDP = num => {
+    let fib = [0, 1]; // fib[0] = 0, fib[1] = 1
+    for (let i = 2; i <= num; i++) {
+        fib.push(fib[i - 1] + fib[i - 2]);
+    }
+
+    return fib[num]; // return num'th fib number
+};
+
+// 2. Print the fibonacci series upto nth Fibonacci number
+const FibonacciSeries = num => {
+    let fib = [0, 1]; // fib[0] = 0, fib[1] = 1
+    for (let i = 2; i <= num; i++) {
+        fib.push(fib[i - 1] + fib[i - 2]);
+    }
+
+    return fib;
+};
+
+// Call the functions
+let n = 6;
+console.log(`The ${n}th Fibonacci Number is ${FibonacciNumberRec(n)}`);
+n = 8;
+console.log(`The ${n}th Fibonacci Number is ${FibonacciNumberDP(n)}`);
+n = 10;
+console.log(`The Fibonacci Series upto ${n}th term is ${FibonacciSeries(n)}`);
+
+// Input:
+// 1.a) n = 6
+// Output :
+// The 6th Fibonacci Number is 8
+// Input:
+// 1.b) n = 8
+// The 8th Fibonacci Number is 21
+// Input:
+// 2. n = 10
+// The Fibonacci Series upto 10th term is 0,1,1,2,3,5,8,13,21,34,55
+
+// Note: This is 0-based i.e, fib[0] = 0, fib[1] = 1, fib[2] = 0 + 1 = 1, fib[3] = 1 + 1 = 2