diff --git a/.gitignore b/.gitignore
index 7a39e24..fc0825f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,6 +4,8 @@
 __pycache__/
 *.py[cod]
 *$py.class
+.python-version
+uv.lock
 
 # C extensions
 *.so
diff --git a/2025/d05.py b/2025/d05.py
index fd6c012..810ef0c 100644
--- a/2025/d05.py
+++ b/2025/d05.py
@@ -1,4 +1,45 @@
-from lib import get_data, Grid2D
+from lib import get_data
 
 data = get_data(__file__)
-print(data)
+
+ranges, ids = data.split("\n\n")
+ids = tuple(map(int, ids.splitlines()))
+ranges = [list(map(int, line.split("-"))) for line in ranges.splitlines()]
+
+updated = True
+while updated:
+    updated = False
+    sorted_ranges = []
+    for lo, up in ranges:
+        assert lo <= up
+        for i in range(len(sorted_ranges)):
+            slo, sup = sorted_ranges[i]
+            if up + 1 < slo:
+                sorted_ranges.insert(i, (lo, up))
+            elif lo < slo:
+                sorted_ranges[i] = (lo, max(up, sup))
+                updated = True
+            elif lo <= sup:
+                sorted_ranges[i] = (slo, max(up, sup))
+                updated = True
+            else:
+                continue
+            break
+        else:
+            sorted_ranges.append((lo, up))
+    ranges = sorted_ranges
+
+
+result_part_1 = 0
+for id_to_check in ids:
+    for lo, up in ranges:
+        if lo <= id_to_check <= up:
+            result_part_1 += 1
+            break
+print(result_part_1)
+
+result_part_2 = 0
+for lo, up in ranges:
+    result_part_2 += up - lo + 1
+print(result_part_2)
+assert result_part_2 == 350780324308385
diff --git a/README.md b/README.md
index 6af0e09..cf8fdc5 100644
--- a/README.md
+++ b/README.md
@@ -16,6 +16,11 @@ stressful and this will actually be more fun. Thank you Eric Wastl and let's go!
   overall but it was fun.
 - Day 4: One of the easier grid based puzzles. Less than five minutes with
   existing grid library.
+- Day 5: A problem with ranges; I decided to implement proper range merging this
+  time because I always kind of avoid that. I could probably decrease the
+  complexity from O(n^2) to O(n log(n)) but I am happy that I've implemented
+  merging at all.
+- Day 6:
 
 
 ## AoC 2024
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..084a1c7
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,10 @@
+[project]
+name = "aocpy"
+version = "0.1.0"
+description = "Make ruff and ty available via uv"
+readme = "README.md"
+requires-python = ">=3.13"
+dependencies = [
+    "ruff>=0.14.11",
+    "ty>=0.0.11",
+]