add old solutions

1 files changed, 16 insertions, 0 deletions

diff --git a/4.lua b/4.lua
new file mode 100644
index 0000000..daec4bc
--- /dev/null
+++ b/4.lua
@@ -0,0 +1,16 @@
+local function is_palindrome(n)
+    local first_half = string.sub(n, 1, string.len(n) / 2)
+    local second_half = string.sub(n, -string.len(n) / 2)
+    return first_half == string.reverse(second_half)
+end
+
+local prods = {}
+for i = 100,999 do
+    for j = 100,i do
+        table.insert(prods, i * j)
+    end
+end
+table.sort(prods, function(a, b) return a > b end)
+for _, v in ipairs(prods) do
+    if is_palindrome(v) then print(v) break end
+end