Submission #2857259

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Source Code Expand

using System;
using System.Linq;
using System.Collections.Generic;
using static System.Console;

class Program {
    internal static void Main(string[] args) {
        int N = int.Parse(ReadLine());
        var A = ReadLine().Split(' ').Select(s => long.Parse(s)).ToList();
        var dic = new Dictionary<long, int>();

        for (int i = 0; i < N; i++) {
            if (dic.ContainsKey(A[i])) {
                dic[A[i]]++;    
            } else {
                dic.Add(A[i], 1);
            }
        }

        var max = dic.OrderByDescending(kvp => kvp.Key).First();
        if (max.Value >= 4) {
            WriteLine(Math.Pow(max.Key, 2));
            return;
        }

        var values = dic.OrderByDescending(kvp => kvp.Key)
                        .Where(kvp => kvp.Value >= 2)
                        .Select(kvp => kvp.Key).ToArray();
        if (values.Length < 2) {
            WriteLine(0);
            return;
        }
        long ans = values[0] * values[1];
        WriteLine(ans);
    }
}

Submission Info

Judge Result