Neetcode Day 1

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217. Contains Duplicate

Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.

My solution:

var containsDuplicate = function(nums) {
    const result = []

    nums.forEach((n) => {
        if (!result.includes(n)) {
            result.push(n)
        }
    })

   return result.length !== nums.length
};

In my solution I fill an array with elements from the nums array only if it doesn't exist in the new array yet.

Upon further review, a much simpler solution would be created using a Set.

var containsDuplicate = function(nums) {
    const newNums = new Set(nums)

    return newNums.size !== nums.length
};

A set is a collection of unique values, which you can compare to the size of the original array as the size would only be different if a non-unique value, or duplicate, appeared.

I wasn't previously aware of the Set.size property so this exercise definitely taught me to not overlook Sets in the future.

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