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perl/Examples/Chap1/hanoi

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+
+
+###
+### hanoi
+###
+
+## Chapter 1 section 3
+
+# hanoi(N, start, end, extra)
+# Solve Tower of Hanoi problem for a tower of N disks,
+# of which the largest is disk #N.  Move the entire tower from
+# peg `start' to peg `end', using peg `extra' as a work space
+  
+sub hanoi {
+  my ($n, $start, $end, $extra) = @_;
+  if ($n == 1) { 
+    print "Move disk #1 from $start to $end.\n";  # Step 1
+  } else {
+    hanoi($n-1, $start, $extra, $end);            # Step 2
+    print "Move disk #$n from $start to $end.\n"; # Step 3
+    hanoi($n-1, $extra, $end, $start);            # Step 4
+  }
+}