Solution: Number of Visible People in a Queue

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

We'll cover the following...

Statement
Solution
- Time complexity
- Space complexity

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

Two Pointers

Fast and Slow Pointers

Sliding Window

Heaps

Modified Binary Search

Dynamic Programming

Topological Sort

Graphs

Tree Breadth First Search

Union Find

Coding Patterns

Solution: Number of Visible People in a Queue

Statement