1.2.3 프로세스가 자라나는 정도 (임시)

object item3 { // do iterating exponention // using when n is even > iter_expt(n/2)*iter_expt(n/2), // b^(n^(m)) = b^(m^(n)) : b^(n/2^(2)) = b^(2^(n/2)) // otherwise (odd) > (iter_expt(n-1, b, a*b)) def expt(n: Int, b: Int): Int = { def iter_expt(n: Int, b: Int, a: Int) : Int = { println("n: " + n + ", b: " + b + ", a: " + a); if (n == 0) 1 else if (n == 1) b*a // for 2, need manual operate for avoiding infinite loop else if (n!=2 && n % 2 == 0) iter_expt(n/2, b*b, 1) else iter_expt(n-1, b, a*b) } iter_expt(n, b, 1) } //> expt: (n: Int, b: Int)Int expt(3, 5) //> n: 3, b: 5, a: 1 //| n: 2, b: 5, a: 5 //| n: 1, b: 5, a: 25 //| res0: Int = 125 } /* 2^2 = 2^((1)^2) = 4 iter_expt(2, iter_expt(1, 2, 1), 1) iter_expt(2, 2, 1) */