Question

How to find whether an array include a pair of which product equals to N in C#

Answer 1

using System;
using System.Collections.Generic;

public class Program 
{
	private static bool ProductExists(int[] arr, int N) {
		int size = arr.Length;

		if (size < 2) {
			return false;
		}

		HashSet<int> set = new HashSet<int>();

		for (int i = 0; i < size; i++) {
			if (arr[i] == 0 && N == 0) {
				return true;
			}
			if (N % arr[i] == 0) {
				if (set.Contains(N / arr[i])) {
					return true;
				}
				set.Add(arr[i]);
			}
		}

		return false;
	}
	public static void Main(string[] args)
	{
		int[] arr = new int[] {5, 7, 13, 25, 9, 3, 4};
		int N = 21;

		if (ProductExists(arr, N))	{
			Console.WriteLine("Yes");
		}
		else {
			Console.WriteLine("No");
		}
	}
}



/*
run:
  
Yes
  
*/

 

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