Sha256: 3bc4e0c120cbb96e64614ec949efb86891aa653b44931a22cd5c918cc36ec3d4
Contents?: true
Size: 1.99 KB
Versions: 26
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Stored size: 1.99 KB
Contents
using System;
using System.Collections.Generic;
using System.Linq;
public static class PalindromeProducts
{
public static (int, IEnumerable<(int,int)>) Largest(int minFactor, int maxFactor)
{
return FindPalindrome(minFactor, maxFactor, x => x.Max(p => p.Item1));
}
public static (int, IEnumerable<(int,int)>) Smallest(int minFactor, int maxFactor)
{
return FindPalindrome(minFactor, maxFactor, x => x.Min(p => p.Item1));
}
private static (int, IEnumerable<(int, int)>) FindPalindrome(int minFactor, int maxFactor,
Func<List<(int, (int, int))>, int> valueSelector)
{
if (minFactor > maxFactor || maxFactor < minFactor)
{
throw new ArgumentException();
}
try
{
var palindromes = FindAllPalindromes(minFactor, maxFactor);
var value = valueSelector(palindromes);
var factors = new HashSet<(int, int)>(palindromes.Where(p => p.Item1 == value).Select(p => p.Item2));
return (value, factors);
} catch (InvalidOperationException)
{
throw new ArgumentException();
}
}
private static List<(int, (int, int))> FindAllPalindromes(int minFactor, int maxFactor)
{
return (from pair in Pairs(minFactor, maxFactor)
let product = pair.Item1 * pair.Item2
where IsPalindrome(product)
select (product, pair))
.ToList();
}
private static IEnumerable<(int, int)> Pairs(int minFactor, int maxFactor)
{
return from x in Enumerable.Range(minFactor, maxFactor + 1 - minFactor)
from y in Enumerable.Range(x, maxFactor + 1 - x)
select (x, y);
}
private static bool IsPalindrome(int num)
{
var n = num;
var rev = 0;
while (num > 0)
{
var dig = num % 10;
rev = rev * 10 + dig;
num = num / 10;
}
return n == rev;
}
}
Version data entries
26 entries across 26 versions & 1 rubygems