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Abhishek Chaudhary
Abhishek Chaudhary

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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
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
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
heights: [1,2,3,4,5]
expected: [1,2,3,4,5]
All indices match.


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


class Solution:
    def heightChecker(self, heights: List[int]) -> int:
        n = len(heights)
        expected = sorted(heights)
        return len([i for i in range(n) if heights[i] != expected[i]])
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