c #编程题，会的直接留下代码，感谢

Write a program that reads two strings s and t, each on its own line. Each string will contain only lowercase letters. The program should print a string u such that

1. Some permutation of u is a subsequence of s.
2. Some permutation of u is a subsequence of t.
3. u is as long as possible.

A subsequence is not necessarily contiguous. If there is more than one longest possible u, print the one that comes first alphabetically.

Sample input:

watermelon
summertime

Output:

eemrt

Sample input #2:

rhinoceros
elephant

Output:

ehn

Hint: If you have an integer i in the range 0 ≤ i < 26 and you want to convert it to a letter from 'a' to 'z', you can do this:

char c = (char) ('a' + i);

是不是你这个测试软件完必须要完全按照给出示例那样，直接输入，输出，不给增加任何其他输出内容的。。我改下逻辑看看。。：~~

我这里VS跑没有问题。。

using System;
using System.Collections.Generic;
using System.Linq;

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            var s = Console.ReadLine();
            var t = Console.ReadLine();
            var arrS = s.ToCharArray();
            var arrT = t.ToCharArray();
            var dit = new Dictionary<char, int>();
            foreach (var c in arrS)
            {
                if (!dit.ContainsKey(c)) dit.Add(c, 0);
                dit[c]++;
            }
            var rst = new List<char>();
            foreach (var c in arrT)
            {
                if (dit.ContainsKey(c))
                {
                    rst.Add(c);
                    dit[c]--;
                    if (dit[c] == 0) dit.Remove(c);
                }
            }

            Console.WriteLine(String.Join("", rst.OrderBy(i => i)));


        }
    }

}

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