feat(problem): 4 - largest palindrome product

src/bin/4.rs

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+/*
+Problem 4 - Largest palindrome product
+
+A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
+Find the largest palindrome made from the product of two 3-digit numbers.
+*/
+
+fn largest_pallindromic_number(lower_bound: usize, upper_bound: usize) -> usize {
+	let mut products: Vec<usize> = vec![];
+	
+	for i in lower_bound..(upper_bound + 1) {
+		for j in lower_bound..(upper_bound + 1) {
+			products.push(i * j);
+		}
+	}
+
+	// Filter for pallindromic numbers
+	let mut pallindromic = products
+		.iter()
+		.filter(|x| x.to_string() == x.to_string().chars().rev().collect::<String>())
+		.collect::<Vec<&usize>>();
+
+	// Return the largest value
+	pallindromic.sort();
+	pallindromic.reverse();
+
+	return *pallindromic[0];
+}
+
+fn main() {
+	let number = largest_pallindromic_number(100, 999);
+	
+	println!("The largest pallindromic number made from the product of two three-digit numbers is {number}");
+}