43 lines
771 B
Go
43 lines
771 B
Go
|
package recursion
|
||
|
|
import "fmt"
|
||
|
|
/*
|
||
|
|
Time: O(2^n)
|
||
|
|
Space: O(n) - call stack
|
||
|
|
*/
|
||
|
|
func fibonacci_using_recursion(n int) int {
|
||
|
|
if n == 2{
|
||
|
|
return 1
|
||
|
|
}
|
||
|
|
if n == 1{
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
return fibonacci_using_recursion(n-1) + fibonacci_using_recursion(n-2)
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
Time: O(N)
|
||
|
|
Space: O(1)
|
||
|
|
*/
|
||
|
|
func fibonacci_using_constant_space(n int) int{
|
||
|
|
first:= 0
|
||
|
|
second:= 1
|
||
|
|
|
||
|
|
for i := 3; i<= n; i++{
|
||
|
|
next:= first + second
|
||
|
|
first = second
|
||
|
|
second = next
|
||
|
|
}
|
||
|
|
|
||
|
|
if n > 1{
|
||
|
|
return second
|
||
|
|
}
|
||
|
|
return first // this handles n == 1 or n == 0 case
|
||
|
|
}
|
||
|
|
|
||
|
|
func run_fibonacci(){
|
||
|
|
n := 10
|
||
|
|
recursionValue := fibonacci_using_recursion(n)
|
||
|
|
nonrecursionValue := fibonacci_using_constant_space(n)
|
||
|
|
fmt.Printf("Recursion value: %d\n", recursionValue)
|
||
|
|
fmt.Printf("Non-recursion value: %d\n", nonrecursionValue)
|
||
|
|
}
|