1608. Special Array with X Elements Greater than or Equal X - Explanation

class Solution:
    def specialArray(self, nums: List[int]) -> int:
        for i in range(1, len(nums) + 1):
            cnt = 0
            for num in nums:
                if num >= i:
                    cnt += 1

            if cnt == i:
                return i

        return -1

class Solution:
    def specialArray(self, nums: List[int]) -> int:
        l, r = 1, len(nums)
        while l <= r:
            mid = (l + r) >> 1
            cnt = sum(1 for num in nums if num >= mid)

            if cnt == mid:
                return mid

            if cnt < mid:
                r = mid - 1
            else:
                l = mid + 1

        return -1

class Solution:
    def specialArray(self, nums: List[int]) -> int:
        nums.sort()
        i = 0
        prev = -1
        total_right = len(nums)
        while i < len(nums):
            if nums[i] == total_right or (prev < total_right < nums[i]):
                return total_right

            while i + 1 < len(nums) and nums[i] == nums[i + 1]:
                i += 1

            prev = nums[i]
            i += 1
            total_right = len(nums) - i

        return -1

class Solution:
    def specialArray(self, nums: List[int]) -> int:
        nums.sort()
        n = len(nums)
        i, j = 0, 1

        while i < n and j <= n:
            while i < n and j > nums[i]:
                i += 1

            if j == n - i:
                return j
            j += 1

        return -1

class Solution:
    def specialArray(self, nums: List[int]) -> int:
        count = [0] * (len(nums) + 1)
        for num in nums:
            index = min(num, len(nums))
            count[index] += 1

        total_right = 0
        for i in range(len(nums), -1, -1):
            total_right += count[i]
            if i == total_right:
                return total_right
        return -1