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Fibonacci.java
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Fibonacci.java
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package DAA_Practicals;
public class Fibonacci {
public static long fibonacciNonRecursive(int n) {
if (n <= 1)
return n;
long fib = 0;
long prev1 = 1;
long prev2 = 0;
for (int i = 2; i <= n; i++) {
fib = prev1 + prev2;
prev2 = prev1;
prev1 = fib;
}
return fib;
}
public static int fibonacciRecursive(int n) {
if (n <= 1)
return n;
return fibonacciRecursive(n - 1) + fibonacciRecursive(n - 2);
}
public static int fibonacciRecursiveDP(int n, int dp[]) {
if (n <= 1)
return n;
if(dp[n]!=0)
return dp[n];
return dp[n]=fibonacciRecursive(n - 1) + fibonacciRecursive(n - 2);
}
public static void main(String[] args) {
int n = 10;
new Thread(() -> {
Thread.currentThread().setName("Fibonacci Recursive Thread");
System.out.println(Thread.currentThread().getName() + " is computing...");
int result1 = fibonacciRecursive(n); // TC: O(2^n), SC: O(n)
System.out.println("Fibonacci Recursive (" + n + ") = " + result1);
System.out.println(Thread.currentThread().getName() + " done.");
}).start();
new Thread(() -> {
Thread.currentThread().setName("Fibonacci Non-Recursive Thread");
System.out.println(Thread.currentThread().getName() + " is computing...");
long result2 = fibonacciNonRecursive(n); // TC: O(n), SC: O(1)
System.out.println("Fibonacci Non-Recursive (" + n + ") = " + result2);
System.out.println(Thread.currentThread().getName() + " done.");
}).start();
new Thread(() -> {
Thread.currentThread().setName("Fibonacci Recursive DP Thread");
System.out.println(Thread.currentThread().getName() + " is computing...");
long result2 = fibonacciRecursiveDP(n,new int[n+1]); // TC: O(n), SC: O(n)
System.out.println("Fibonacci Recursive DP (" + n + ") = " + result2);
System.out.println(Thread.currentThread().getName() + " done.");
}).start();
}
}
// Output
// Fibonacci Non-Recursive Thread is computing...
// Fibonacci Recursive DP Thread is computing...
// Fibonacci Recursive Thread is computing...
// Fibonacci Non-Recursive (10) = 55
// Fibonacci Recursive (10) = 55
// Fibonacci Non-Recursive Thread done.
// Fibonacci Recursive DP (10) = 55
// Fibonacci Recursive DP Thread done.
// Fibonacci Recursive Thread done.