removeDuplicatesFromSortedArray.js

'use strict';

const removeDuplicates = function(nums) {
  let i = 0;
  for (let j = 1; j < nums.length; j++) {
      if (nums[i] != nums[j]) {
        i++;
        nums[i] = nums[j];
      }
  }
  return i + 1;
}

let i = 0;
for (let j = 1; j < nums.length; j++) {
  if (nums[i] === nums[j]) {
    nums.slice(i, j + 1);
  }
}
return nums;

// another way without making an extra space (O(1))
const removeDuplicates = function(nums) {
  // make a function that returns a unique value
  function unique(num, index) {
    return nums.indexOf(num) === index;
  }

  // filter the array with unique values using a separate function
  nums = nums.filter(unique);

  // return the length of the array
  return nums.length;
}

// O(N) memory
// const removeDuplicates = function(nums) {
// 	// make a Set to store unique values
// 	let set = new Set();

// 	// add each element of the array to the Set
// 	for (let num of nums) {
// 		set.add(num);
// 	}
	
// 	// return the size of the Set
// 	return set.size;
// }

let nums = [0,0,1,1,1,2,2,3,3,4];
console.log(removeDuplicates(nums));