Added Quiz 5 for pointers. Elephants!!!

1 files changed, 45 insertions, 0 deletions

diff --git a/exercises/44_quiz5.zig b/exercises/44_quiz5.zig
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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"); // single quotes
+
+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);
+}
+
+// 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;
+    }
+}