Problem

Do not allocate extra space for another array, you must do this in place with constant memory.

The order of elements can be changed. It doesn’t matter what you leave beyond the new length.

Example:
Given input array nums = [3,2,2,3], val = 3

Your function should return length = 2, with the first two elements of nums being 2.

My Solution

class Solution {
    public int removeElement(int[] nums, int val) {
        int length = nums.length;
        for (int i = 0; i < length; i++) {
            if (nums[i] == val) {
                remove(nums, i, length);
                length--;
                i--;
            }
        }
        return length;
    }
    
    public void remove(int[] nums, int i, int length) {
        for (int j = i; j < length - 1; j++) {
            nums[j] = nums[j+1];
        }
    }
}

Great Solution

public int removeElement(int[] nums, int val) {
    int i = 0;
    for (int j = 0; j < nums.length; j++) {
        if (nums[j] != val) {
            nums[i] = nums[j];
            i++;
        }
    }
    return i;
}