Grokking the Coding Interview Patterns in C#/

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Solution: Number of Visible People in a Queue

Let’s solve the Number of Visible People in a Queue problem using the Stacks pattern.

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Statement

You are given an array heights representing n people standing in a queue, numbered from 0 to n - 1 from left to right. Each element heights[i] denotes the height of the person at position i. All heights are distinct.

A person at position i can see a person at position j (i < j) to their right if every person between them is shorter than both heights[i] and heights[j].

Formally, person i can see person j if:

$i < j$ and $m i n (h e i g h t s [i], h e i g h t s [j]) > m a x (h e i g h t s [i + 1], h e i g h t s [i + 2], . . ., h e i g h t s [j - 1])$ ...