Init

.github/workflows/python-app.yml

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+# This workflow will install Python dependencies, run tests and lint with a single version of Python
+# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-python
+
+name: Python application
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+  workflow_dispatch:
+    inputs:
+      tags:
+        description: "Test python build"
+        required: false
+        type: string
+
+
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+    - name: Set up Python 3.10
+      uses: actions/setup-python@v3
+      with:
+        python-version: "3.10"
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install pylint pytest
+        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+    - name: Lint with pylint
+      run: |
+        pylint *.py
+    - name: Test with pytest
+      run: |
+        pytest

.gitignore

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+.pytest_cache
+__pycache__

main.py

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+from priority_queue import PriorityQueue
+def main():
+    pq = PriorityQueue()
+
+    pq.push("Task 1", 3)
+    pq.push("Task 2", 1)
+    pq.push("Task 3", 2)
+
+    print(pq.pop())
+    print(pq.pop())
+    print(pq.pop())
+
+if __name__ == "__main__":
+    main()

priority_queue.py

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+class PriorityQueue:
+  def __init__(self):
+    self.heap = []
+
+  def push(self, item, priority):
+    entry = (priority, item)
+    self.heap.append(entry)
+    self._sift_up(len(self.heap) - 1)
+
+  def pop(self):
+    if len(self.heap) > 1:
+      self._swap(0, len(self.heap) - 1)
+      priority, item = self.heap.pop()
+      self._sift_down(0)
+      return item
+    elif len(self.heap) == 1:
+      priority, item = self.heap.pop()
+      return item
+    else:
+      return None
+
+  def _sift_up(self, index):
+    while index > 0:
+      parent_index = (index - 1) // 2
+      if self.heap[parent_index][0] > self.heap[index][0]:
+        self._swap(parent_index, index)
+        index = parent_index
+      else:
+        break
+
+  def _sift_down(self, index):
+    while True:
+      left_child_index = 2 * index + 1
+      right_child_index = 2 * index + 2
+      smallest = index
+
+      if left_child_index < len(self.heap) and \
+        self.heap[left_child_index][0] > self.heap[smallest][0]:
+        smallest = left_child_index
+
+      if right_child_index < len(self.heap) and \
+        self.heap[right_child_index][0] > self.heap[smallest][0]:
+        smallest = right_child_index
+
+      if smallest != index:
+        self._swap(index, smallest)
+        index = smallest
+      else:
+        break
+
+  def _swap(self, i, j):
+    self.heap[i], self.heap[j] = self.heap[j], self.heap[i]