##### Welcome to Subscribe On Youtube

Formatted question description: https://leetcode.ca/all/1051.html

# 1051. Height Checker (Easy)

Students are asked to stand in non-decreasing 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 non-decreasing 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 (0-based) we have 4 vs 1 so we have to move this student.
On index 4 (0-based) we have 1 vs 3 so we have to move this student.
On index 5 (0-based) 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

Related Topics:
Array

## Solution 1.

• class Solution {
public int heightChecker(int[] heights) {
int length = heights.length;
int[] sorted = new int[length];
System.arraycopy(heights, 0, sorted, 0, length);
Arrays.sort(sorted);
int count = 0;
for (int i = 0; i < length; i++) {
if (heights[i] != sorted[i])
count++;
}
return count;
}
}

############

class Solution {
public int heightChecker(int[] heights) {
int[] expected = heights.clone();
Arrays.sort(expected);
int ans = 0;
for (int i = 0; i < heights.length; ++i) {
if (heights[i] != expected[i]) {
++ans;
}
}
return ans;
}
}

• // OJ: https://leetcode.com/problems/height-checker/
// Time: O(NlogN)
// Space: O(N)
class Solution {
public:
int heightChecker(vector<int>& A) {
auto B = A;
sort(begin(B), end(B));
int ans = 0;
for (int i = 0; i < A.size(); ++i) ans += A[i] != B[i];
return ans;
}
};

• class Solution:
def heightChecker(self, heights: List[int]) -> int:
expected = sorted(heights)
return sum(a != b for a, b in zip(heights, expected))

############

class Solution(object):
def heightChecker(self, heights):
"""
:type heights: List[int]
:rtype: int
"""
return sum(a != b for a, b in zip(sorted(heights), heights))

• func heightChecker(heights []int) int {
expected := make([]int, len(heights))
copy(expected, heights)
sort.Ints(expected)
ans := 0
for i, v := range heights {
if v != expected[i] {
ans++
}
}
return ans
}