1051.HeightChecker.cs

// 1051. Height Checker
// 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

public class Solution {
    public int HeightChecker(int[] heights) {
        int[] expected = (int[])heights.Clone();
        Array.Sort(expected);
        int count = 0;
        for (int i = 0; i < heights.Length; i++) {
            if (heights[i] != expected[i])
                count++;
        }
        return count;
    }
}