76 lines
1.7 KiB
Java
76 lines
1.7 KiB
Java
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<Integer,Integer> map = new HashMap<Integer,Integer>();
|
|
|
|
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<Integer,Integer> fib = new HashMap<Integer,Integer>();
|
|
|
|
for (int i=1;i<n+1;i++) {
|
|
int f = 1;
|
|
if (i<=2) {
|
|
f = 1;
|
|
}
|
|
else {
|
|
f = fib.get(i-1) + fib.get(i-2);
|
|
}
|
|
fib.put(i, f);
|
|
}
|
|
|
|
return fib.get(n);
|
|
}
|
|
}
|
|
|