DOCS: Find the first palindrome description fixes (#79)

challenges/find-the-first-palindrome/description.md

@@ -1,21 +1,27 @@
-In this challenge, you will demonstrate your understanding of **control flow** in Rust. The task involves finding the first **palindrome number** in a given range.
+In this challenge, you will demonstrate your understanding of **control flow** in Rust. The task involves finding the first **decimal palindrome** in a given range.
 
-### What's a palindrome?
+### What's a decimal palindrome?
 
-**A palindrome is a number that reads the same backward as forward**. This exercise will require you to iterate through the range, check each number to see if it is a palindrome, and return the first palindrome found. You can use any **control flow** construct to solve this problem.
+**A decimal palindrome is a number whose decimal (base 10, "normal") digits read the same backward as forward**. This exercise will require you to find the numerically least non-negative palindrome in a given range. The easiest way to do this is to iterate through the range, check each number to see if it is a palindrome, and return the first palindrome found. You can use any **control flow** construct to solve this problem. (There are much more efficient ways to solve this problem, but the calculations get complex quickly.)
 
-Palindromes are fascinating numbers, and finding them within a range will require efficient control flow logic to ensure you identify the first one accurately.
+Palindromes are fascinating numbers, and finding them within a range will require clear control flow logic to ensure you identify the first one accurately.
 
 ## Your task
 
-You need to write a function, `find_first_palindrome(start: i32, end: i32) -> Option<i32>`, that takes two **integer** arguments `start` and `end`. The function should return the first palindrome number within the range (inclusive). If there are no palindromes in the range, it should return `None`.
+You need to write a function, `find_first_palindrome(start: i32, end: i32) -> Option<i32>`, that takes two **integer** arguments `start` and `end`. The function should return the numerically least non-negative palindrome number within the range.
+
+* The range is inclusive: for example, if `start == 1` and `end == 1` the palindrome `1` is in range.
+
+* The range may have `start > end`, in which case it is still a valid range: for example, `start == 3` and `end == 1` contains the values `1, 2, 3`.
+
+If there are no palindromes in the range, the function should return `None`.
 
 ## Requirements
 
-- The function should iterate through the numbers from `start` to `end`.
-- It should check each number to determine if it is a **palindrome**.
-- The function should **return the first palindrome found**, or `None` if no palindromes exist in the range.
-- You must handle cases where `start` may be greater than `end`.
+- The function should cover the numbers from `start` to `end` inclusive.
+- It should check each non-negative number to determine if it is a **palindrome**.
+- The function should **return the numerically least palindrome found**, or `None` if no palindromes exist in the range.
+- You must handle "reversed" ranges, when `start` is greater than `end`.
 
 ## Example
 
@@ -28,16 +34,24 @@ assert_eq!(result, Some(101)); // 101 is the first palindrome in the range
 
 let result = find_first_palindrome(123, 130);
 assert_eq!(result, None); // No palindromes in this range
+
+let result = find_first_palindrome(-130, -1);
+assert_eq!(result, None); // No palindromes in this range
+
+let result = find_first_palindrome(100, -105);
+assert_eq!(result, Some(0)); // 0 is the first palindrome in the range
 ```
 
 ## Did you know?
 
-Did you know that **palindromes** are not just limited to numbers? They are found in **words, phrases, and even DNA sequences!** For example, the word **"racecar"** is a palindrome, as it reads the same backward and forward. **Palindromes** are fascinating in various fields, including mathematics, literature, and biology, where they often have unique properties and significance.
+Did you know that **palindromes** are not just limited to numbers? They are found in **words, phrases, and even DNA sequences!** For example, the word **"racecar"** is a palindrome, as it reads the same backward and forward. Check out this ["Weird Al" video](https://youtu.be/JUQDzj6R3p4) for many many examples.
+
+**Palindromes** are fascinating in various fields, including mathematics, literature, and biology, where they often have unique properties and significance.
 
 ## Hints
 
-- To check if a number is a palindrome, convert it to a **string** and compare it with its **reverse**.
-- You can get the **reverse** by using the `rev()` method on a `char`.
-- You can get the `char`s in a **string** by using the `chars()` method on a `String`
+- To check if a number is a palindrome, you probably want to convert it to a `String` and compare it with its **reverse**.
+- You can get the `char`s in a `String` by using the `chars()` method on a `String`
+- You can iterate over values in reverse order by using the `rev()` method on an iterator. For example, you can get the `char`s in a `String` `s` in reverse order with `s.chars().rev()`
 - Use a **loop**, iterator, or any other **control flow** construct to check each number in the range until a **palindrome** is found or the range is exhausted.
-- Remember to handle the case **where start is greater than end** by swapping the values if necessary.
+- Remember to handle the case **where start is greater than end**, probably by swapping the values if necessary.