336. 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:
Input: heights = [1,1,4,2,1,3]
Output: 3

Explanation: Expected: [1,1,1,2,3,4]. Indices 2, 4, 5 mismatch.

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