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