# 1051. Height Checker

## Description

A school is trying to take an annual photo of all the students. The students are asked to stand in a single file line in non-decreasing order by height. Let this ordering be represented by the integer array expected where expected[i] is the expected height of the ith student in line.

You are given an integer array heights representing the current order that the students are standing in. Each heights[i] is the height of the ith student in line (0-indexed).

Return the number of indices where heights[i] != expected[i].

Example 1:

Input: heights = [1,1,4,2,1,3]
Output: 3
Explanation:
heights:  [1,1,4,2,1,3]
expected: [1,1,1,2,3,4]
Indices 2, 4, and 5 do not match.


Example 2:

Input: heights = [5,1,2,3,4]
Output: 5
Explanation:
heights:  [5,1,2,3,4]
expected: [1,2,3,4,5]
All indices do not match.


Example 3:

Input: heights = [1,2,3,4,5]
Output: 0
Explanation:
heights:  [1,2,3,4,5]
expected: [1,2,3,4,5]
All indices match.


Constraints:

• 1 <= heights.length <= 100
• 1 <= heights[i] <= 100

## Solutions

• 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;
}
}

• class Solution {
public:
int heightChecker(vector<int>& heights) {
vector<int> expected = heights;
sort(expected.begin(), expected.end());
int ans = 0;
for (int i = 0; i < heights.size(); ++i) ans += heights[i] != expected[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))


• 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
}

• function heightChecker(heights: number[]): number {
const expected = [...heights].sort((a, b) => a - b);
return heights.reduce((acc, cur, i) => acc + (cur !== expected[i] ? 1 : 0), 0);
}