2018: d07: ex2: add solution

2018/d07/ex2/ex2.py

@@ -0,0 +1,67 @@
+#!/usr/bin/env python
+
+import sys
+from collections import defaultdict
+from typing import NamedTuple
+
+
+class Point(NamedTuple):
+    x: int
+    y: int
+
+
+def solve(input: str) -> int:
+    def parse(input: list[str]) -> dict[str, set[str]]:
+        graph: dict[str, set[str]] = defaultdict(set)
+        for line in input:
+            split = line.split()
+            prev, after = split[1], split[7]
+            graph[after].add(prev)
+            graph[prev]  # Ensure that all nodes are in the dictionary
+        return graph
+
+    def job_done(graph: dict[str, set[str]], job: str) -> None:
+        assert not graph.pop(job)  # Sanity check
+        for node in graph:
+            graph[node].discard(job)
+
+    def next_job(graph: dict[str, set[str]], ongoing: list[str]) -> str | None:
+        return min(
+            (n for n, deps in graph.items() if not deps and n not in ongoing),
+            default=None,
+        )
+
+    def assemble(graph: dict[str, set[str]], additional_time: int, workers: int) -> int:
+        res = 0
+        worker_time = [0] * workers
+        worker_jobs = [""] * workers
+        while graph:
+            # Step to the next worker, ignoring idle workers, with a default for the first step
+            dt = min((t for t in worker_time if t > 0), default=0)
+            res += dt
+            worker_time = [max(0, t - dt) for t in worker_time]
+            for i in range(workers):
+                if worker_time[i] != 0:
+                    continue
+                if worker_jobs[i] != "":
+                    job_done(graph, worker_jobs[i])
+                    worker_jobs[i] = ""
+                if (job := next_job(graph, worker_jobs)) is None:
+                    continue
+                worker_time[i] = additional_time + ord(job) - ord("A") + 1
+                worker_jobs[i] = job
+        assert all(j == "" for j in worker_jobs)  # Sanity check
+        assert all(t == 0 for t in worker_time)  # Sanity check
+        return res
+
+    graph = parse(input.splitlines())
+    return assemble(graph, 60, 5)
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()