389.查出两个字符串中 不同的字母 Find the Difference

Given two strings s and t which consist of only lowercase letters.

String t is generated by random shuffling string s and then add one more letter at a random position.

Find the letter that was added in t.Input:

解题思路：用字典存储每个字母的出现次数

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Algorithm;
namespace Solution {
    public class Solution {
        public char FindTheDifference(string s, string t) {
            var d = new Dictionary<char, int>();
            foreach (var c in s) {
                if (d.ContainsKey(c)) d[c]++;
                else d[c] = 1;
            }
            foreach (var c in t) {
                if (d.ContainsKey(c)) d[c]++;
                else d[c] = 1;
            }
            foreach (var i in d.Keys) {
                if (d[i] % 2 != 0) {
                    return i;
                }
            }
            return ' ';
        }
    }
    class Program {
        static void Main(string[] args) {
            Solution s = new Solution();
            var res = s.FindTheDifference("abcdef", "abcde");
            Console.WriteLine(res);
        }
    }
}

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