Move Zeros

Problem Statement

Given an array of integers, move all zeros to the end of the array while maintaining the relative order of non zero elements.

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Examples

Input
arr = [0, 1, 0, 3, 12]

Output
[1, 3, 12, 0, 0]

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Input
arr = [0, 0, 1]

Output
[1, 0, 0]

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Approach 1 Using Extra Space

Create a new array to store non zero elements first and then append zeros.

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Steps

1 Traverse the array and store non zero elements
2 Count number of zeros
3 Append zeros at the end

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Code

```python id="mz1"
def moveZeros(arr):
result = []
zero_count = 0

for num in arr:
    if num != 0:
        result.append(num)
    else:
        zero_count += 1

for _ in range(zero_count):
    result.append(0)

return result

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## Approach 2 In Place Method

Rearrange elements within the same array.

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### Steps

1 Initialize index for non zero elements
2 Traverse the array
3 If element is non zero swap it with current index
4 Increment index

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### Code



```python id="mz2"
def moveZeros(arr):
    j = 0

    for i in range(len(arr)):
        if arr[i] != 0:
            arr[i], arr[j] = arr[j], arr[i]
            j += 1

    return arr

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Explanation

The idea is to push all non zero elements to the front while shifting zeros to the end. The order of non zero elements remains unchanged.

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Expected Output

Input
arr = [0, 1, 0, 3, 12]

Output
[1, 3, 12, 0, 0]

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Conclusion

Moving zeros to the end is a common problem that helps in understanding array manipulation and in place operations. It is frequently asked in coding interviews.

Practice this problem with different inputs to improve your coding skills.