# Move all zeros to start and ones to end in an Array of random integers in C++

C++Server Side ProgrammingProgramming

In this tutorial, we are going to write a program that moves all zeroes to front and ones to end of the array.

Let's see the steps to solve the problem.

• Initialise the array.

• Initialise an index to 1.

• Iterate over the given array.

• If the current element is not zero, then update the value at the index with the current element.

• Increment the index.

• Write a loop that iterates from the above index to n

• Update all the elements to 1.

• Similarly, do for 0. Instead of increasing the index, decrease it to move all zeroes to front of the array.

## Example

Let's see the code.

Live Demo

#include <bits/stdc++.h>
using namespace std;
void update1And0Positions(int arr[], int n) {
int index = 0;
for (int i = 0; i < n; i++) {
if (arr[i] != 1) {
arr[index++] = arr[i];
}
}
while (index < n) {
arr[index++] = 1;
}
index = 0;
for (int i = n - 1; i >= 0; i--) {
if (arr[i] == 1) {
continue;
}
if (!index) {
index = i;
}
if (arr[i] != 0) {
arr[index--] = arr[i];
}
}
while (index >= 0) {
arr[index--] = 0;
}
}
int main() {
int arr[] = { 4, 5, 1, 1, 0, 0, 2, 0, 3, 1, 0, 1 };
int n = 12;
update1And0Positions(arr, n);
for (int i = 0; i < n; i++) {
cout << arr[i] << " ";
}
cout << endl;
return 0;
}

## Output

If you run the above code, then you will get the following result.

0 0 0 0 4 5 2 3 1 1 1 1

## Conclusion

If you have any queries in the tutorial, mention them in the comment section.