Python Program to Sort an array of 0s, 1s and 2s
Last Updated :
11 May, 2020
Given an array A[] consisting 0s, 1s and 2s. The task is to write a function that sorts the given array. The functions should put all 0s first, then all 1s and all 2s in last.
Examples:
Input : {0, 1, 2, 0, 1, 2, 2, 2, 2, 1}
Output : {0, 0, 1, 1, 1, 2, 2, 2, 2, 2}
Input : {0, 1, 1, 0, 1, 2, 1, 2, 0, 0, 0, 1}
Output : {0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2}
Simple Solution : We create three empty lists. We add all 0s to first list, 1s to second list and 2s to third list. Finally we append all lists and return
def SortWithoutSorting(arr):
l1 = []
l2 = []
l3 = []
for i in range ( len (arr)):
if arr[i] = = 0 :
l1.append(arr[i])
elif arr[i] = = 1 :
l2.append(arr[i])
else :
l3.append(arr[i])
return (l1 + l2 + l3)
arr = array.array( 'i' , [ 0 , 1 , 0 , 1 , 2 , 2 , 0 , 1 ])
print (SortWithoutSorting(arr))
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Efficient Solution The above solution requires extra space. How to do it without extra space (in-place) in the same given list and using only one traversal. Please refer Sort an array of 0s, 1s and 2s for implementation of the efficient solution.
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