2025 day 2 part 1

2025/day02/range/item/main.tf

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+variable "half" {
+  type = number
+}
+
+output "full" {
+  value = tonumber("${var.half}${var.half}")
+}

2025/day02/range/main.tf

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+variable "min" {
+  type = number
+}
+
+variable "max" {
+  type = number
+}
+
+locals {
+  digits       = floor(length(tostring(var.max)) / 2)
+  maximum      = substr(tostring(var.max), 0, local.digits)
+  real_maximum = length(tostring(var.max)) % 2 == 0 ? tonumber(local.maximum) : pow(10, local.digits)
+
+  min_digits = max(floor(length(tostring(var.min)) / 2), 1)
+  minimum    = tonumber(substr(tostring(var.min), 0, local.min_digits))
+
+  count = max(local.real_maximum - local.minimum + 1, 1)
+
+  can_work = anytrue([for n in range(length(tostring(var.min)), length(tostring(var.max)) + 1) : n % 2 == 0])
+}
+
+// This "candidates" module ought really be a list comprehension from range, but Terraform does not
+// allow you to create ranges longer than 1024.
+module "candidates" {
+  source = "./item"
+  count  = local.can_work ? local.count : 0
+  half   = count.index + local.minimum
+}
+
+locals {
+  valid = [for n in module.candidates[*].full : n if n >= var.min && n <= var.max]
+}
+
+output "invalid_sum" {
+  value = length(local.valid) > 0 ? sum(local.valid) : 0
+}