Question

你好，我一直在努力实现这种选择排序已经有好几天了。我觉得我的代码很接近它，但无法弄清楚为什么我没有得到它。

这是我的代码

def selectionSort(aList):

    #For each index in the list...
    for i in range(len(aList)):

        #Assume first that current item is already correct...
        minIndex = i

        #For each index from i to the end...
        for j in range(i + 1, len(aList)):

            if aList[j] >= aList[j - 1]:
                break
            aList[j], aList[j - 1] = aList[j - 1], aList[j]
            minIndex = aList.index(aList[j - 1])

        #Save the current minimum value since we're about
        #to delete it
        minValue = aList[minIndex]

        #Delete the minimum value from its current index
        del aList[minIndex]

        #Insert the minimum value at its new index
        aList.insert(i, minValue)

    #Return the resultant list
    return aList

这是我得到的结果

[4, 2, 1, 3, 5]

而不是：

[1, 2, 3, 4, 5]

感谢您的提前帮助

Answer 1

for j in range(i + 1, len(aList)):

        if aList[j] >= aList[j - 1]:
            break
        aList[j], aList[j - 1] = aList[j - 1], aList[j]
        minIndex = aList.index(aList[j - 1])

选择排序是通过迭代地找到列表中的最小元素来进行排序。只需将第一个元素设置为最小值，遍历列表，如果当前元素小于最小值，则将其记录为最小值并记录其索引。之后的部分是正确的。

Answer 2

以下是工作代码人员：

def selectionSort(aList):

    #For each index in the list...
    for i in range(len(aList)):

        minIndex = i

        #For each index from i+1 to the end...
        for j in range(i + 1, len(aList)):

            if aList[minIndex] > aList[j]:
            minIndex = j

        #Save the current minimum value since we're about
        #to delete it
        minValue = aList[minIndex]

        #Delete the minimum value from its current index
        del aList[minIndex]

        #Insert the minimum value at its new index
        aList.insert(i, minValue)

    #Return the resultant list
    return aList

再次感谢。不能相信只有两行代码给了我一个噩梦。 pheew

Answer 3

你不需要删除和插入，只需交换em！

import System.IO

readListOfLists :: Handle -> IO [[Int]]
readListOfLists handle = do 
    contents <- hGetContents handle
    let ls :: [String] 
        ls = lines contents
        ws :: [[String]]
        ws= map words ls
        res :: [[Int]]
        res = map (map read) ws
    return res;

Selectionsort不输出正确的结果Python

3 个答案: