diff --git a/Dynamic Programming/Fibonacci.java b/Dynamic Programming/Fibonacci.java new file mode 100644 index 000000000..72048153d --- /dev/null +++ b/Dynamic Programming/Fibonacci.java @@ -0,0 +1,75 @@ +import java.io.BufferedReader; +import java.io.InputStreamReader; +import java.util.HashMap; +import java.util.Map; + +/** + * + * @author Varun Upadhyay (https://github.com/varunu28) + * + */ + +public class Fibonacci { + + public static Map map = new HashMap(); + + public static void main(String[] args) throws Exception { + + BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); + int n = Integer.parseInt(br.readLine()); + + System.out.println(fibMemo(n)); // Returns 8 for n = 6 + System.out.println(fibBotUp(n)); // Returns 8 for n = 6 + } + + /** + * This method finds the nth fibonacci number using memoization technique + * + * @param n The input n for which we have to determine the fibonacci number + * Outputs the nth fibonacci number + **/ + + public static int fibMemo(int n) { + if (map.containsKey(n)) { + return map.get(n); + } + + int f; + + if (n <= 2) { + f = 1; + } + else { + f = fib(n-1) + fib(n-2); + map.put(n,f); + } + + return f; + } + + /** + * This method finds the nth fibonacci number using bottom up + * + * @param n The input n for which we have to determine the fibonacci number + * Outputs the nth fibonacci number + **/ + + public static int fibBotUp(int n) { + + Map fib = new HashMap(); + + for (int i=1;i