Issue #31 (Parallel processing) is completed

Author: Hamid Gasmi

2-data-sructures-fundamentals/3_priority_queues_and_disjoint_sets/job_queue.py

@@ -0,0 +1,85 @@
+from collections import namedtuple
+
+AssignedJob = namedtuple("AssignedJob", ["worker", "started_at"])
+
+def leftChild(i, size):
+    l = 2 * i + 1
+    return l if l < size else -1
+
+def rightChild(i, size):
+    r = 2 * i + 2
+    return r if r < size else -1
+
+def IsHigherPriority(minHeap, i, j, size):
+    
+    if j >= size or j < 0:
+        return False
+    if i >= size or i < 0:
+        return False
+
+    if minHeap[i].started_at < minHeap[j].started_at:
+        return True
+    elif minHeap[i].started_at == minHeap[j].started_at and minHeap[i].worker < minHeap[j].worker:
+        return True
+
+    return False
+
+# Time Complexity: O(log J)
+# Space Complexity: O(1)
+def siftDown(minHeap, i, size):
+    if i >= size:
+        return
+
+    indexMin = i
+    if IsHigherPriority(minHeap, leftChild(i, size), indexMin, size):
+        indexMin = leftChild(i, size)
+
+    if IsHigherPriority(minHeap, rightChild(i, size), indexMin, size):
+        indexMin = rightChild(i, size)
+
+    if indexMin != i:
+        minHeap[i], minHeap[indexMin] = minHeap[indexMin], minHeap[i]
+        siftDown(minHeap, indexMin, size)
+
+# Time Complexity: O(N * log J)
+# Space Complexity: O(J)
+def assign_jobs(n_workers, jobs):
+    result = []
+    
+    #Build a MinHeap
+    minHeapPriority = [AssignedJob(i, 0) for i in range(n_workers) ] # O(n)
+
+    for job in jobs: # O(j * log n)
+        
+        result.append(AssignedJob(minHeapPriority[0].worker, minHeapPriority[0].started_at))
+        minHeapPriority[0] = AssignedJob(minHeapPriority[0].worker, minHeapPriority[0].started_at + job)
+
+        # Sift Down the work which started_at time is just changed
+        siftDown(minHeapPriority, 0, n_workers) # O(log n)
+
+    return result
+
+# Time Complexity: O(N * J)
+# Space Complexity: O(J)
+def assign_jobs_brute(n_workers, jobs):
+    result = []
+    next_free_time = [0] * n_workers
+    for job in jobs:
+        next_worker = min(range(n_workers), key=lambda w: next_free_time[w])
+        result.append(AssignedJob(next_worker, next_free_time[next_worker]))
+        next_free_time[next_worker] += job
+
+    return result
+
+def main():
+    n_workers, n_jobs = map(int, input().split())
+    jobs = list(map(int, input().split()))
+    assert len(jobs) == n_jobs
+
+    assigned_jobs = assign_jobs(n_workers, jobs)
+
+    for job in assigned_jobs:
+        print(job.worker, job.started_at)
+
+if __name__ == "__main__":
+    main()