# 1608. Special Array With X Elements Greater Than or Equal X

## Description

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

## Solutions

• class Solution {
public int specialArray(int[] nums) {
for (int x = 1; x <= nums.length; ++x) {
int cnt = 0;
for (int v : nums) {
if (v >= x) {
++cnt;
}
}
if (cnt == x) {
return x;
}
}
return -1;
}
}

• class Solution {
public:
int specialArray(vector<int>& nums) {
for (int x = 1; x <= nums.size(); ++x) {
int cnt = 0;
for (int v : nums) cnt += v >= x;
if (cnt == x) return x;
}
return -1;
}
};

• class Solution:
def specialArray(self, nums: List[int]) -> int:
for x in range(1, len(nums) + 1):
cnt = sum(v >= x for v in nums)
if cnt == x:
return x
return -1


• func specialArray(nums []int) int {
for x := 1; x <= len(nums); x++ {
cnt := 0
for _, v := range nums {
if v >= x {
cnt++
}
}
if cnt == x {
return x
}
}
return -1
}

• function specialArray(nums: number[]): number {
const n = nums.length;
for (let i = 0; i <= n; i++) {
if (i === nums.reduce((r, v) => r + (v >= i ? 1 : 0), 0)) {
return i;
}
}
return -1;
}


• impl Solution {
pub fn special_array(nums: Vec<i32>) -> i32 {
let n = nums.len() as i32;
for i in 0..=n {
let mut count = 0;
for &num in nums.iter() {
if num >= i {
count += 1;
}
}
if count == i {
return i;
}
}
-1
}
}