chap18.py 文件源码

def nsmallest(n, a):
    h = []
    for e in a[:n]:
        heapq.heappush(h, -e)  # we use a max heap but push -1 * e
    for e in a[n:]:
        heapq.heappushpop(h, -e)
    return -heapq.heappop(h)