Codeforces 567A: Lineland Mail - Solution & Explanation (C++/Python)

In this video, we solve **Codeforces Problem 567A: Lineland Mail**.
This is a great problem to practice greedy logic and working with sorted arrays and coordinate geometry on a 1D axis.

*🧠 The Problem Logic:*
We are given $n$ cities on a number line (sorted in ascending order). For every city, we need to find:

1. *Minimum Cost (Nearest Neighbor):* Since the array is sorted, the nearest city to city $i$ must be either its left neighbor ($i-1$) or its right neighbor ($i+1$).
2. *Maximum Cost (Farthest Neighbor):* The farthest city from city $i$ is always one of the endpoints of the line: either the very first city ($0$) or the very last city ($n-1$).

We can calculate this for every city in just one loop\!

*🔗 Problem Link:*
[https://codeforces.com/problemset/problem/...](https://codeforces.com/problemset/problem/...)

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*📊 Complexity Analysis:*

*Time Complexity:* $O(N)$ - We iterate through the list of cities exactly once.
*Space Complexity:* $O(N)$ - To store the coordinates of the cities.

*👨‍💻 Code Snippet Logic:*

```cpp
// For Min: min(abs(x[i] - x[i-1]), abs(x[i] - x[i+1]))
// For Max: max(abs(x[i] - x[0]), abs(x[i] - x[n-1]))
```

Hi, I'm Ajmain Fayek Diganta, a CSE student at BUET. I upload tutorials on Competitive Programming, LeetCode, and Algorithms to help you crack coding interviews and contests.

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