Add Code For nth Fibonacci Number in c

Author: keshavagarwal17

fibonacci_number/FibonacciNumber.c

@@ -0,0 +1,43 @@
+#include<stdio.h>
+
+long long int fibonacci(long long int n)
+{
+	//Because first fibonacci number is 0 and second fibonacci number is 1.
+	if(n==1 || n==2)
+	{
+		return (n-1);
+	}
+	else
+	{
+		//store last fibonacci number
+		long long int a=1;
+		//store second last fibonacci number 
+		long long int b=0;
+		//store current fibonacci number
+		long long int nth_Fib;
+		for(long long int i=3;i<=n;i++)
+		{
+			nth_Fib = a+b;
+			b = a;
+			a = nth_Fib;
+		}
+		return nth_Fib;
+	}
+}
+
+int main()
+{
+	long long int n;
+	printf("Enter a Number : ");
+	scanf("%lli",&n);
+	if(n<1)
+	{
+		printf("Number must be greater than 0");
+	}
+	else
+	{
+		long long int nth_Fib = fibonacci(n);
+		printf("Fibonacci Number is %lli",nth_Fib);
+	}
+	return 0;
+}