day 2 puzzle 1

progress.yaml

@@ -1,2 +1,4 @@
 1:
   stars: 2
+2:
+  stars: 1

res/examples/day2.txt

@@ -0,0 +1,6 @@
+7 6 4 2 1
+1 2 7 8 9
+9 7 6 2 1
+1 3 2 4 5
+8 6 4 4 1
+1 3 6 7 9

src/day2/puzzle1.typ

@@ -0,0 +1,35 @@
+#import "/src/utils.typ": *
+
+#let solve(input) = {
+  let safe-cnt = 0
+  for line in input.split("\n") {
+    let nums = line.split(" ").map(n => int(n))
+
+    let increasing
+    let safe = true
+    for i in range(nums.len() - 1) {
+      let d = nums.at(i + 1) - nums.at(i)
+      let abs-d = calc.abs(d)
+      if abs-d < 1 or abs-d > 3 {
+        safe = false
+        break
+      }
+      if i == 0 {
+        increasing = d > 0
+      } else if (d > 0) != increasing {
+        safe = false
+        break
+      }
+    }
+    if safe {
+      safe-cnt += 1
+    }
+  }
+  return safe-cnt
+}
+
+#show-puzzle(
+  2, 1,
+  solve,
+  example: 2
+)