Given an array of random numbers, Push all the zeros of a given array to the end of the array. For example, if the given arrays is {1, 9, 8, 4, 0, 0, 2, 7, 0, 6, 0}, it should be changed to {1, 9, 8, 4, 2, 7, 6, 0, 0, 0, 0}. The order of all other elements should be same. Expected time complexity is O(n) and extra space is O(1). Examples:
Input : arr = [1, 2, 0, 4, 3, 0, 5, 0] Output : arr = [1, 2, 4, 3, 5, 0, 0, 0] Input : arr = [1, 2, 0, 0, 0, 3, 6] Output : arr = [1, 2, 3, 6, 0, 0, 0]
We have existing solution for this problem please refer Move all zeroes to end of array link. We will solve this problem in python using List Comprehension in a single line of code.
Implementation:
Python
# Function to append all zeros at the end# of arraydef moveZeros(arr): # first expression returns a list of # all non zero elements in arr in the # same order they were inserted into arr # second expression returns a list of # zeros present in arr return [nonZero for nonZero in arr if nonZero!=0] + \ [Zero for Zero in arr if Zero==0]# Driver functionif __name__ == "__main__": arr = [1, 2, 0, 4, 3, 0, 5, 0] print (moveZeros(arr)) |
[1, 2, 4, 3, 5, 0, 0, 0]
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Approach#2: Using while loop
This approach moves all zeroes in an input array to the end of the array while keeping the non-zero elements in their original order. It uses two pointers to keep track of the positions of the zeroes and non-zeroes in the array, and swaps them as necessary.
Algorithm
1. Initialize two pointers i and j to 0.
2. Traverse the array with j and for each non-zero element, swap arr[i] and arr[j] and increment i.
3. Return the resulting array.
Python3
def move_zeroes(arr): i, j = 0, 0 while j < len(arr): if arr[j] != 0: arr[i], arr[j] = arr[j], arr[i] i += 1 j += 1 return arrarr=[1, 2, 0, 4, 3, 0, 5, 0]print(move_zeroes(arr)) |
[1, 2, 4, 3, 5, 0, 0, 0]
Time Complexity: O(n)
Auxiliary Space: O(1)
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