python - 如何实现适用于负数的 CountingSort？

Question

我在 Python 中实现了以下计数排序算法，但它不适用于包含负数的数组。有人可以帮助我吗？

def counting(nlist):
    nlist = list(nlist)
    size = len(nlist)

    if size < 2:
        return nlist

    k = max(nlist)

    counter = [0] * ( k + 1 )

    for i in nlist:
        counter[i] += 1

    ndx = 0;
    for i in range( len( counter ) ):
        while 0 < counter[i]:
           nlist[ndx] = i
           ndx += 1
           counter[i] -= 1

   return nlist

Answer 1

一个简单的方法就是找到最小值并将您的索引偏移该数量，以便最小值存储在 counter 的数组索引 0 中。然后在你的 while 循环中，重新添加最小值以获得原始值:

m = min(nlist)
k = max(nlist) - m

counter = [0] * ( k + 1 )

for i in nlist:
    counter[i-m] += 1

ndx = 0;
for i in range( len( counter ) ):
    while 0 < counter[i]:
       nlist[ndx] = i+m
       ndx += 1
       counter[i] -= 1