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+//
+// "Elephants walking
+// Along the trails
+//
+// Are holding hands
+// By holding tails."
+//
+// from Holding Hands
+// by Lenore M. Link
+//
+const std = @import("std");
+
+const Elephant = struct {
+ letter: u8,
+ tail: *Elephant = undefined,
+ visited: bool = false,
+};
+
+pub fn main() void {
+ var elephantA = Elephant{ .letter = 'A' };
+ // (Please add Elephant B here!)
+ var elephantC = Elephant{ .letter = 'C' };
+
+ // Link the elephants so that each tail "points" to the next elephant.
+ // They make a circle: A->B->C->A...
+ elephantA.tail = &elephantB;
+ // (Please link Elephant B's tail to Elephant C here!)
+ elephantC.tail = &elephantA;
+
+ visitElephants(&elephantA);
+
+ std.debug.print("\n", .{});
+}
+
+// This function visits all elephants once, starting with the
+// first elephant and following the tails to the next elephant.
+// If we did not "mark" the elephants as visited (by setting
+// visited=true), then this would loop infinitely!
+fn visitElephants(first_elephant: *Elephant) void {
+ var e = first_elephant;
+
+ while (!e.visited) {
+ std.debug.print("Elephant {u}. ", .{e.letter});
+ e.visited = true;
+ e = e.tail;
+ }
+}