Implement 2024 day 13 in terraform

2024/bonus/day13/solve/main.tf

@@ -0,0 +1,34 @@
+variable "machines" {
+  type = list(list(number))
+}
+
+locals {
+  a_substitutions = [
+    for machine in var.machines :
+    [-machine[2] / machine[0], machine[4] / machine[0]]
+  ]
+
+  b_equations = [
+    for i in range(length(var.machines)) :
+    [
+      var.machines[i][3] + local.a_substitutions[i][0] * var.machines[i][1],
+      var.machines[i][5] - local.a_substitutions[i][1] * var.machines[i][1]
+    ]
+  ]
+
+  b = [for eq in local.b_equations : floor(eq[1] / eq[0] + 0.5)]
+
+  a = [
+    for i in range(length(var.machines)) :
+    floor((var.machines[i][4] - local.b[i] * var.machines[i][2]) / var.machines[i][0] + 0.5)
+  ]
+}
+
+output "solutions" {
+  value = sum([
+    for i in range(length(var.machines)) :
+    3 * local.a[i] + local.b[i]
+    if var.machines[i][0] * local.a[i] + var.machines[i][2] * local.b[i] == var.machines[i][4]
+    && var.machines[i][1] * local.a[i] + var.machines[i][3] * local.b[i] == var.machines[i][5]
+  ])
+}