1608. Special Array With X Elements Greater Than or Equal X(Solution || Leetcode easy || Java)

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

SOLUTION:

class Solution {
    public int specialArray(int[] nums) {
      //First sort the array
        Arrays.sort(nums);
       
      //Initialise variable to check if this the element
      // we are searching for
        int i = 1;

      //Initialise varibale to work as index for us
        int j = 0;

        while(j < nums.length){

      //if the number i is less than or eqaul to the element
      //we are at and, i is also equal to remaning length after it 
      //then i is our answer
            if(nums[j] >= i && i == nums.length - j){
                return i;
            }
            else if(nums[j] < i){
                j++;
            }
            else{
                i++;
            }
        }
        
    //if we do not found any such number return -1
      return -1;
    }
}

Runtime: 1 ms, faster than 92.50% of Java online submissions for Special Array With X Elements Greater Than or Equal X.

Memory Usage: 39.9 MB, less than 93.52% of Java online submissions for Special Array With X Elements Greater Than or Equal X.

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