How hard is LeetCode 1051. Height Checker?

LeetCode 1051. Height Checker is rated Easy on LeetCode.

What is the time complexity of LeetCode 1051. Height Checker?

The Python solution on this page runs in O(n \times \log n).

What is the space complexity of LeetCode 1051. Height Checker?

The Python solution on this page uses O(n) auxiliary space.

What topics does LeetCode 1051. Height Checker cover?

LeetCode 1051. Height Checker is tagged Array, Counting Sort and Sorting on LeetCode.

Height Checker — LeetCode 1051 Python Solution

EasyArrayCounting SortSorting

Problem: #1051
Pattern: Sorting
Reading time: 2 min
Source: leetcode.com

The problem

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.

Example

Input: heights = [1,1,4,2,1,3]
Output: 3
Explanation: heights: [1,1,4,2,1,3]

Python solution

Python

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

Complexity

Measure	Complexity
Time	O(n \times \log n)
Space	O(n) auxiliary

Pattern: Sorting

Spend O(n log n) once to buy an ordering that makes the rest of the problem trivial. LeetCode 1051. Height Checker is filed here because LeetCode tags it Sorting and Counting Sort, which is the vocabulary this hub collects.

The sorting guide has the Python template for the pattern and the 401 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 1051. Height Checker?: LeetCode 1051. Height Checker is rated Easy on LeetCode.
What is the time complexity of LeetCode 1051. Height Checker?: The Python solution on this page runs in O(n \times \log n).
What is the space complexity of LeetCode 1051. Height Checker?: The Python solution on this page uses O(n) auxiliary space.
What topics does LeetCode 1051. Height Checker cover?: LeetCode 1051. Height Checker is tagged Array, Counting Sort and Sorting on LeetCode.