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What is this?

The rules of the game are explained in my original post.

14th Challenge

Challenge

Euler Challange 4

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.

Solution

First I tried it with number manipulation and recursion, but somehow it was easier with strings.

	fn euler4(){

	    let mut largest_prod = 0;
	    let mut prod ;

	    const RANGE: Range<u64> = 100..1000;

	    for x in RANGE {
	        for y in RANGE {
	            prod =x*y;

	            if prod > largest_prod && is_palindrome(prod){
	                largest_prod = prod;

	            }
	        }
	    }

	    println!("largest palindrome which is product of two three digit numbers = {}",largest_prod)
	}

	#[test]
	fn test_is_palindrome(){
	    assert!(!is_palindrome(99002275));
	    assert!(is_palindrome(332233));
	    assert!(is_palindrome(332233332233));
	    assert!(is_palindrome(99999999));
	    assert!(!is_palindrome(94));
	    assert!(!is_palindrome(994));
	    assert!(!is_palindrome(12345678));
	    assert!(!is_palindrome(971198));
	    assert!(!is_palindrome(963342));

	}

	fn is_palindrome(x:u64) -> bool{
	    let mut s = x.to_string();

	    while s.len() >= 2 {
	        if s.ends_with(s.chars().nth(0).unwrap()) {
	            if s.len() == 2 {
	                return s.chars().nth(0) == s.chars().nth(1)
	            }
	            s.remove(0);
	            s.remove(s.len()-1);
	            println!("{}",s)
	        }else{
	            return false
	        }

	    }

	    false
	}

See github and playground