快速排序:
#QuickSort by Alvindef QuickSort(myList,start,end): #判斷low是否小于high,如果為false,直接返回 if start < end: i,j = start,end #設置基準數 base = myList[i] while i < j: #如果列表后邊的數,比基準數大或相等,則前移一位直到有比基準數小的數出現 while (i < j) and (myList[j] >= base): j = j - 1 #如找到,則把第j個元素賦值給第個元素i,此時表中i,j個元素相等 myList[i] = myList[j] #同樣的方式比較前半區 while (i < j) and (myList[i] <= base): i = i + 1 myList[j] = myList[i] #做完第一輪比較之后,列表被分成了兩個半區,并且i=j,需要將這個數設置回base myList[i] = base #遞歸前后半區 QuickSort(myList, start, i - 1) QuickSort(myList, j + 1, end) return myListmyList = [49,38,65,97,76,13,27,49]歸并排序:def mergesort(seq): if len(seq)<=1: return seq mid=int(len(seq)/2) left=mergesort(seq[:mid]) right=mergesort(seq[mid:]) return merge(left,right)def merge(left,right): result=[] i,j=0,0 while i<len(left) and j<len(right): if left[i]<=right[j]: result.append(left[i]) i+=1 else: result.append(right[j]) j+=1 result+=left[i:] result+=right[j:] return resultif __name__=='__main__': seq=[4,5,7,9,7,5,1,0,7,-2,3,-99,6] print(mergesort(seq))新聞熱點
疑難解答
