day 7 puzzle 1

progress.yaml

@@ -9,4 +9,6 @@
 5:
   stars: 2
 6:
+  stars: 1
+7:
   stars: 1

res/examples/day7.txt

@@ -0,0 +1,9 @@
+190: 10 19
+3267: 81 40 27
+83: 17 5
+156: 15 6
+7290: 6 8 6 15
+161011: 16 10 13
+192: 17 8 14
+21037: 9 7 18 13
+292: 11 6 16 20

src/day7/puzzle1.typ

@@ -0,0 +1,42 @@
+#import "/src/utils.typ": *
+
+#let solveable(values, target) = {
+  if values.len() == 1 {
+    return values.last() == target
+  }
+
+  let values = values
+  let v = values.pop()
+  if calc.rem(target, v) == 0 {
+    if solveable(values, target / v) {
+      return true
+    }
+  }
+  if v > target {
+    return false
+  }
+
+  return solveable(values, target - v)
+}
+
+#let solve(input) = {
+  let equations = input.split("\n")
+
+  let total = 0
+  for equation in equations {
+    let (target, values) = equation.split(": ")
+    target = int(target)
+    values = values.split(" ").map(int)
+
+    if solveable(values, target) {
+      total += target
+    }
+  }
+  return total
+}
+
+#show-puzzle(
+  7, 1,
+  solve,
+  example: 3749
+)