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Add tests, remove main, add negativity test in Fibonacci.java (#5645)

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Hardik Pawar
2024-10-10 00:50:45 +05:30
committed by GitHub
parent 4a0e46dae6
commit ce9f42081d
3 changed files with 109 additions and 15 deletions
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34
src/main/java/com/thealgorithms/dynamicprogramming/Fibonacci.java
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@ -2,7 +2,6 @@ package com.thealgorithms.dynamicprogramming;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
/**
* @author Varun Upadhyay (https://github.com/varunu28)
@ -11,27 +10,19 @@ public final class Fibonacci {
private Fibonacci() {
}
private static final Map<Integer, Integer> CACHE = new HashMap<>();
public static void main(String[] args) {
// Methods all returning [0, 1, 1, 2, 3, 5, ...] for n = [0, 1, 2, 3, 4, 5, ...]
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
System.out.println(fibMemo(n));
System.out.println(fibBotUp(n));
System.out.println(fibOptimized(n));
System.out.println(fibBinet(n));
sc.close();
}
static final Map<Integer, Integer> CACHE = new HashMap<>();
/**
* 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
* @throws IllegalArgumentException if n is negative
*/
public static int fibMemo(int n) {
if (n < 0) {
throw new IllegalArgumentException("Input n must be non-negative");
}
if (CACHE.containsKey(n)) {
return CACHE.get(n);
}
@ -52,8 +43,12 @@ public final class Fibonacci {
*
* @param n The input n for which we have to determine the fibonacci number
* Outputs the nth fibonacci number
* @throws IllegalArgumentException if n is negative
*/
public static int fibBotUp(int n) {
if (n < 0) {
throw new IllegalArgumentException("Input n must be non-negative");
}
Map<Integer, Integer> fib = new HashMap<>();
for (int i = 0; i <= n; i++) {
@ -80,9 +75,13 @@ public final class Fibonacci {
* Time Complexity will be O(n)
* <p>
* Whereas , the above functions will take O(n) Space.
* @throws IllegalArgumentException if n is negative
* @author Shoaib Rayeen (https://github.com/shoaibrayeen)
*/
public static int fibOptimized(int n) {
if (n < 0) {
throw new IllegalArgumentException("Input n must be non-negative");
}
if (n == 0) {
return 0;
}
@ -105,9 +104,14 @@ public final class Fibonacci {
* = 1.6180339887... Now, let's look at Binet's formula: Sn = Φⁿ–(– Φ⁻ⁿ)/√5 We first calculate
* the squareRootof5 and phi and store them in variables. Later, we apply Binet's formula to get
* the required term. Time Complexity will be O(1)
* @param n The input n for which we have to determine the fibonacci number
* Outputs the nth fibonacci number
* @throws IllegalArgumentException if n is negative
*/
public static int fibBinet(int n) {
if (n < 0) {
throw new IllegalArgumentException("Input n must be non-negative");
}
double squareRootOf5 = Math.sqrt(5);
double phi = (1 + squareRootOf5) / 2;
return (int) ((Math.pow(phi, n) - Math.pow(-phi, -n)) / squareRootOf5);