ziglings/exercises/044_quiz5.zig

//
//    "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 elephantB = Elephant{ .letter = 'B' };
  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!)
  elephantB.tail = &elephantC;
  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;
  }
}