Merge remote-tracking branch 'upstream/master'

1 files changed, 22 insertions, 0 deletions

diff --git a/challenge-146/laurent-rosenfeld/lua/ch-2.lua b/challenge-146/laurent-rosenfeld/lua/ch-2.lua
new file mode 100644
index 0000000000..bb1e3c546c
--- /dev/null
+++ b/challenge-146/laurent-rosenfeld/lua/ch-2.lua
@@ -0,0 +1,22 @@
+-- For a node `x/y` with a fraction less than 1, the parent is `x/(y-x)`;
+-- For a node `x/y` with a fraction larger than 1, the parent is `(x-y)/x`.
+
+local function get_parent(pair)
+    num = pair[1]
+    denom = pair[2]
+    -- no ternary operator in Lua, we can simulate it with and / or:
+    return num < denom and {num, denom - num} or {num - denom, denom}
+end
+
+local function to_str(pair)
+    -- return pair[1] .. "/" .. pair[2]
+    return table.concat(pair, "/")
+end
+
+local tests = { {5, 2}, {2, 5}, {3, 4}, {3,5} }
+for _, test in pairs(tests) do
+    parent = get_parent(test)
+    gd_parent = get_parent(parent)
+    print("Node " .. to_str(test) .. " - Parent: " .. to_str(parent)
+        .. " - Grand-Parent: " .. to_str(gd_parent))
+end