Remove Element

05 Mar, 2021

Problem

Given an array nums and a value val, remove all instances of that value in-place and return the new length.

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

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

Clarification:

Confused why the returned value is an integer but your answer is an array?

Note that the input array is passed in by reference, which means a modification to the input array will be known to the caller as well.

Internally you can think of this:

// nums is passed in by reference. (i.e., without making a copy)
int len = removeElement(nums, val);

// any modification to nums in your function would be known by the caller.
// using the length returned by your function, it prints the first len elements.

for (int i = 0; i < len; i++) {
	print(nums[i]);
}

Example 1:

Input: nums = [3,2,2,3], val = 3
Output: 2, nums = [2,2]
// Explanation: Your function should return length = 2,
// with the first two elements of nums being 2.
// It doesn't matter what you leave beyond the returned length.
// For example if you return 2 with nums = [2,2,3,3] or nums = [2,2,0,0],
// your answer will be accepted.

Example 2:

Input: nums = [0,1,2,2,3,0,4,2], val = 2
Output: 5, nums = [0,1,4,0,3]
// Explanation: Your function should return length = 5,
// with the first five elements of nums containing 0, 1, 3, 0, and 4.
// Note that the order of those five elements can be arbitrary.
// It doesn't matter what values are set beyond the returned length.

Constraints:

0 <= nums.length <= 100
0 <= nums[i] <= 50
0 <= val <= 100

My Solution

success

var removeElement = function (nums, val) {
	for (let i = 0; i < nums.length; i++) {
		if (nums[i] === val) {
			nums.splice(i, 1, '');
		}
	}
	nums.sort().reverse();
	let cnt = 0;
	for (let j = 0; j < nums.length; j++) {
		if (nums[j] !== '') {
			cnt++;
		}
	}
	return cnt;
};