Towers of Hanoi: Difference between revisions

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 procedure hanoi(n, needle1, needle2)   #: solve towers of hanoi by moving  n disks from needle 1 to needle2 via other
 local other
-/needle1 := 1                             # 1 default
+n := integer(0 < n) | runerr(n,101)       # 1 ensure integer (this also ensures it's positive too)
-/needle2 := 2                             # 2 default
+/needle1 := 1                             # 2 default
-n := integer(0 < n) | runerr(n,101)       # 3 ensure integer (this also ensures it's positive too)
+/needle2 := 2                             # 3 default
 if n = 1 then
    write("Move disk from ", needle1, " to ", needle2)
 else {
-   other := 6 - needle1 - needle2   # clever but somewhat un-iconish way to find other
+   other := 6 - needle1 - needle2         # clever but somewhat un-iconish way to find other
-   hanoi(n-1, needle1, other)       # n-1, src, via, dest
+   hanoi(n-1, needle1, other)
    write("Move disk from ", needle1, " to ", needle2)
-   hanoi(n-1, other, needle2)       # n-1, via, dist, src
+   hanoi(n-1, other, needle2)
 }
 return
 end</lang>
 ==={{header|Unicon}}===
 This Icon solution works in Unicon.