Try to solve this at https://algodaily.com/challenges/least-missing-positive-number We have an unsorted array of integers such as the following: ```js [0, 3, -1, -2, 1] ``` In the above example, the minimum number is `-2` and the maximum is `3`. If it were sorted, it would look like: ```js [-2, -1, 0, 1, 3] ``` This means there is an `expected range` (defined as the collection of values between the minimum and maximum values) of `[-2, -1, 0, 1, 2, 3]` for the array. But look at the example again: ```js [-2, -1, 0, 1, 3] ``` We're missing a number: `2`. The *smallest missing positive integer* for our input array is `2`. Can you write a method that takes such an array and returns the first missing positive integer? ```js leastMissingPositive([1, 2, 3, 0]) // 4 ``` In the above example, it is `4` since we already have `0` through `3`. Have your code run in `O(n)` time with constant space (hence, we can easily determine if it was sorted, but most sorts will take `O(n * log n)` time).