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
Solution:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace LeetCode.AskGif.Easy.Array
{
public class HeightCheckerSoln
{
public int HeightChecker(int[] heights)
{
var copy = new int[heights.Length];
copy = heights;
copy = copy.OrderBy(c => c).ToArray();
int count = 0;
for (int i = 0; i < heights.Length; i++)
{
if (copy[i] != heights[i])
{
count++;
}
}
return count;
}
}
}
Time Complexity: O(nlogn)
Space Complexity: O(n)
Unit Tests:
using LeetCode.AskGif.Easy.Array;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Collections.Generic;
using System.Text;
namespace CodingUnitTest.Easy.Array
{
[TestClass]
public class HeightCheckerSolnTests
{
[TestMethod]
public void HeightCheckerSoln_First()
{
var arr = new int[] { 1, 1, 4, 2, 1, 3 };
var expected = 3;
var res = new HeightCheckerSoln().HeightChecker(arr);
Assert.AreEqual(expected, res);
}
[TestMethod]
public void HeightCheckerSoln_Second()
{
var arr = new int[] { 5, 1, 2, 3, 4 };
var expected = 5;
var res = new HeightCheckerSoln().HeightChecker(arr);
Assert.AreEqual(expected, res);
}
[TestMethod]
public void HeightCheckerSoln_Third()
{
var arr = new int[] { 1, 2, 3, 4, 5 };
var expected = 0;
var res = new HeightCheckerSoln().HeightChecker(arr);
Assert.AreEqual(expected, res);
}
}
}
