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