Find out first unique element from array

Hello..., let's find how how we can find the unique element from an array from an unsorted array which has duplicate values -

let's initialize an array -

let a = [1,2,2,3,4,1,5,6,6,7]

and create a variable and initialize it with a[0] value -

let r = a[0]

now the main part, to iterate through array and find out the element with no duplicate value without creating any data structure and in single for loop -

for(let i=0; i<a.length; i++){
    r = r ^ a[i] 
    // here ^ is a bitwise XOR operator which gives a unique value. Here is how it works - if a value is same it gives 0 to it and if its a unique it returns 1 and for the value which is unique we get 1 and this is how we can find out unique element
}

here is the complete code at one -

let a = [1,2,2,3,4,1,5,6,6,7]
let r = a[0]
for(let i=0; i<a.length; i++){
    r = r ^ a[i]
}

Hope it helped you and you found it valuable.

Comments

[Jake Lundberg]

Love that you're sharing with the community! This unfortunately doesn't work though.

Here are a couple of example arrays that cause issues

This array will return 3 which is the last unique number.
let a = [1, 3, 2, 2];

This array will return 2 which is not unique;
let a = [1, 3, 1, 2, 2];

What do you think might be causing this?

[An Architect]

This solution is not full proof working for finding the correct unique. Sometime this can give you a number out from your array.
Try out for : [1,2,2,7,1] and let me know the result.