public class Solution
extends Object
1608 - Special Array With X Elements Greater Than or Equal X\.
Easy
You are given an array `nums` of non-negative integers. `nums` is considered **special** if there exists a number `x` such that there are **exactly** `x` numbers in `nums` that are **greater than or equal to** `x`.
Notice that `x` **does not** have to be an element in `nums`.
Return `x` _if the array is **special** , otherwise, return_ `-1`. It can be proven that if `nums` is special, the value for `x` is **unique**.
**Example 1:**
**Input:** nums = [3,5]
**Output:** 2
**Explanation:** There are 2 values (3 and 5) that are greater than or equal to 2.
**Example 2:**
**Input:** nums = [0,0]
**Output:** -1
**Explanation:** No numbers fit the criteria for x.
If x = 0, there should be 0 numbers >= x, but there are 2.
If x = 1, there should be 1 number >= x, but there are 0.
If x = 2, there should be 2 numbers >= x, but there are 0.
x cannot be greater since there are only 2 numbers in nums.
**Example 3:**
**Input:** nums = [0,4,3,0,4]
**Output:** 3
**Explanation:** There are 3 values that are greater than or equal to 3.
**Constraints:**
* `1 <= nums.length <= 100`
* `0 <= nums[i] <= 1000`