using System;
using System.Collections.Generic;
class MainClass {
// Given an array, return the first recurring value
// Example input: {2, 5, 1, 2, 3, 5, 1, 2, 4} should return 2
// Example input: {2, 1, 1, 2, 3, 4, 1, 2, 4} should return 1
// Example input: {2, 3, 4, 5} should return undefined (-1)
static void Main() {
Console.WriteLine("Hello World!");
int[] array1 = {2, 5, 1, 2, 3, 5, 1, 2, 4};
int[] array2 = {2, 1, 1, 2, 3, 4, 1, 2, 4};
int[] array3 = {2, 3, 4, 5};
Console.WriteLine("First recurring value in array1 is "
+ FirstRecurring(array1));
Console.WriteLine("First recurring value in array2 is "
+ FirstRecurring(array2));
Console.WriteLine("First recurring value in array3 is "
+ FirstRecurring(array3));
}
public static int FirstRecurring(int[] array) {
Dictionary<int, int> dict = new Dictionary<int, int>();
for (int i = 0; i < array.Length; i++) {
if (dict.ContainsKey(array[i])) {
return array[i];
}
dict.Add(array[i], 1);
}
return -1;
}
}
