1. Remove duplicate elements from array without using any library or native function and explain complexity here code example

Example 1: remove duplicates from array

let chars = ['A', 'B', 'A', 'C', 'B'];
let uniqueChars = [...new Set(chars)];

console.log(uniqueChars);

output:
[ 'A', 'B', 'C' ]

Example 2: remove duplicates in sorted array python

j = 0

// traverse elements of arr
for i=0 to n-2
    // if ith element is not equal to (i+1)th element of arr, then store ith value in arr[j]
    if arr[i] != arr[i+1]
        arr[j] = arr[i]
        j += 1

// store last value of arr in temp
arr[j] = arr[n-1]
j += 1

// print first j elements of array arr
for i=0 to j-1 
    print arr[i]