some more days

2018/day7/day7.py

@@ -0,0 +1,88 @@
+#!/usr/bin/env python3
+import re
+from bisect import insort
+from collections import defaultdict
+
+
+def topological_sort(graph, reverse_deps):
+    # find starting nodes: with no incoming edges (aka indegree 0)
+    queue = sorted([task for task in graph.keys() if reverse_deps[task] == set()])
+    order = []
+    seen = set()
+    while queue != []:
+        current = queue.pop(0)
+        if current not in seen:
+            seen.add(current)
+            order.append(current)
+            # add dependencies if all prerequisites are already visited,
+            # insert them in alphabetical order
+            for d in graph[current]:
+                if all(x in order for x in reverse_deps[d]):
+                    insort(queue, d)
+    return order
+
+
+def main(inp):
+    dependencies = defaultdict(set)
+    reverse_deps = defaultdict(set)
+    for l in inp:
+        first, second = re.findall(r"[sS]tep (\w)", l)
+        dependencies[first].add(second)
+        reverse_deps[second].add(first)
+
+    order = topological_sort(dependencies, reverse_deps)
+    print("Part 1: ", "".join(order))
+
+
+    done = []
+    doing = dict()
+
+    workers = 5
+    step = 0
+    number_of_tasks = len(order)
+    while len(done) != number_of_tasks:
+        assert len(doing) <= workers
+        for i in range(workers):
+            # check if the worker has a pending task
+            if i in doing:
+                task = doing[i]
+                if is_task_done(task, step):
+                    #print(f"{step}: worker #{i}, task {task} done")
+                    del doing[i]
+                    done.append(task[0])
+                else:
+                    continue
+            next_task = get_task(dependencies, reverse_deps, done, doing)
+            if next_task is not None:
+                #print(f"{step}: worker #{i}, starting task {next_task}")
+                doing[i] = (next_task, step)
+        #print(f"{step}: {doing} {done}")
+        if len(done) == number_of_tasks:
+            break
+        step += 1
+        print(f"{step}\t{'\t'.join(x[0] for x in doing.values())}")
+    print(step)
+
+def get_task(graph, reverse_deps, done, doing):
+    queue = sorted([task for task in graph.keys() if all(x in done for x in reverse_deps[task])])
+    doingg = [x[0] for x in doing.values()]
+    for t in queue:
+        if t not in done and t not in doingg:
+            return t
+    return None
+
+
+def is_task_done(task, step):
+    letter, start_t = task
+    duration = ord(letter) - ord("A") + 61
+    if step - start_t >= duration:
+        return True
+    return False
+
+
+if __name__ == '__main__':
+    import sys
+    infile = sys.argv[1] if len(sys.argv) > 1 else "example.txt"
+    with open(infile) as inp:
+        main([l.rstrip() for l in inp.readlines()])
+