最大K个数问题的Python版解法总结

import heapq
def get_least_numbers_big_data(self, alist, k):
  max_heap = []
  length = len(alist)
  if not alist or k <= 0 or k > length:
    return
  k = k - 1
  for ele in alist:
    ele = -ele
    if len(max_heap) <= k:
      heapq.heappush(max_heap, ele)
    else:
      heapq.heappushpop(max_heap, ele)

  return map(lambda x:-x, max_heap)


if __name__ == "__main__":
  l = [1, 9, 2, 4, 7, 6, 3]
  min_k = get_least_numbers_big_data(l, 3)

def qselect(A,k): 
  if len(A)<k:return A 
  pivot = A[-1] 
  right = [pivot] + [x for x in A[:-1] if x>=pivot] 
  rlen = len(right) 
  if rlen==k: 
    return right 
  if rlen>k: 
    return qselect(right, k) 
  else: 
    left = [x for x in A[:-1] if x<pivot] 
    return qselect(left, k-rlen) + right 
 
for i in range(1, 10): 
  print qselect([11,8,4,1,5,2,7,9], i)