Heapq Usage Example

heapq.py

class Solution(object):
  def maxAverageRatio(self, classes, extraStudents):
      maxHeap = []
      def delta(a, b):
          return float(a + 1) / (b + 1) — float(a) / b
      for a, b in classes:
          heapq.heappush(maxHeap, (-delta(a, b), a, b))
      for _ in range(extraStudents):
          d, a, b = heapq.heappop(maxHeap)
          heapq.heappush(maxHeap, (-delta(a+1, b+1), a+1, b+1))
      ans = 0.0
      while maxHeap:
          _, a, b = heapq.heappop(maxHeap)
          ans += float(a) / b
      return ans / len(classes)