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1 // Basic Part about the 3n+1 conjecture |
1 // Core Part 1 about the 3n+1 conjecture |
2 //================================== |
2 //================================== |
3 |
3 |
4 // generate jar with |
4 // generate jar with |
5 // > scala -d collatz.jar collatz.scala |
5 // > scala -d collatz.jar collatz.scala |
6 |
6 |
16 val all = for (i <- (1L to bnd)) yield (collatz(i), i) |
16 val all = for (i <- (1L to bnd)) yield (collatz(i), i) |
17 all.maxBy(_._1) |
17 all.maxBy(_._1) |
18 } |
18 } |
19 |
19 |
20 //collatz_max(1000000) |
20 //collatz_max(1000000) |
21 //collatz_max(10000000) |
21 |
22 //collatz_max(100000000) |
|
23 |
22 |
24 /* some test cases |
23 /* some test cases |
25 val bnds = List(10, 100, 1000, 10000, 100000, 1000000) |
24 val bnds = List(10, 100, 1000, 10000, 100000, 1000000) |
26 |
25 |
27 for (bnd <- bnds) { |
26 for (bnd <- bnds) { |
29 println(s"In the range of 1 - ${bnd} the number ${max} needs the maximum steps of ${steps}") |
28 println(s"In the range of 1 - ${bnd} the number ${max} needs the maximum steps of ${steps}") |
30 } |
29 } |
31 |
30 |
32 */ |
31 */ |
33 |
32 |
|
33 |
34 def is_pow(n: Long) : Boolean = (n & (n - 1)) == 0 |
34 def is_pow(n: Long) : Boolean = (n & (n - 1)) == 0 |
35 |
35 |
36 def is_hard(n: Long) : Boolean = is_pow(3 * n + 1) |
36 def is_hard(n: Long) : Boolean = is_pow(3 * n + 1) |
37 |
37 |
38 def last_odd(n: Long) : Long = |
38 def last_odd(n: Long) : Long = |
39 if (is_hard(n)) n else |
39 if (is_hard(n)) n else |
40 if (n % 2 == 0) last_odd(n / 2) else |
40 if (n % 2 == 0) last_odd(n / 2) else |
41 last_odd(3 * n + 1) |
41 last_odd(3 * n + 1) |
42 |
42 |
43 |
43 |
|
44 |
44 //for (i <- 130 to 10000) println(s"$i: ${last_odd(i)}") |
45 //for (i <- 130 to 10000) println(s"$i: ${last_odd(i)}") |
45 //for (i <- 1 to 100) println(s"$i: ${collatz(i)}") |
46 //for (i <- 1 to 100) println(s"$i: ${collatz(i)}") |
46 |
47 |
47 } |
48 } |
48 |
49 |