The Array Height Checker Problem in Java
The challenge
Students are asked to stand in nondecreasing order of heights for an annual photo.
Return the minimum number of students that must move in order for all students to be standing in nondecreasing order of height.
Notice that when a group of students is selected they can reorder in any possible way between themselves and the non selected students remain on their seats.
Example 1:
Input: heights = [1,1,4,2,1,3] Output: 3 Explanation: Current array : [1,1,4,2,1,3] Target array : [1,1,1,2,3,4] On index 2 (0based) we have 4 vs 1 so we have to move this student. On index 4 (0based) we have 1 vs 3 so we have to move this student. On index 5 (0based) we have 3 vs 4 so we have to move this student.
Example 2:
Input: heights = [5,1,2,3,4] Output: 5
Example 3:
Input: heights = [1,2,3,4,5] Output: 0
Constraints:
1 <= heights.length <= 100
1 <= heights[i] <= 100
The solution
The easiest way to solve this is to sort a copy of the array, then compare which values are different.

