Longest Substring with At Most Two Distinct Characters

来源：互联网发布：mysql 集群编辑：程序博客网时间：2024/04/28 06:22

Given a string, find the length of the longest substring T that contains at most 2 distinct characters.

For example, Given s = “eceba”,

T is “ece” which its length is 3.

namespace ConsoleApplication3{    using System;    using System.Collections.Generic;    class Program    {        private static string maxSubStrWithNChars(string str, int n)        {            if (n < 1)                return "";            int s = 0, e = 0, maxS = 0, maxLen = 0;            Dictionary<char, int> dic = new Dictionary<char, int>();            while (s <= e && e < str.Length)            {                while (e < str.Length && dic.Count <= n)                {                    if (!dic.ContainsKey(str[e]))                    {                        dic.Add(str[e], 1);                    }                    else                    {                        ++dic[str[e]];                    }                    if (e - s + 1 > maxLen && dic.Count <= n)                    {                        maxLen = e - s + 1;                        maxS = s;                    }                    ++e;                }                while (s <= e && dic.Count > n)                {                    if (--dic[str[s]] == 0)                    {                        dic.Remove(str[s]);                    }                    ++s;                }            }            return str.Substring(maxS, maxLen);        }        static void Main(string[] args)        {            string str1 = "";                //expect: 0 ""            string str2 = "a";                //expect: 1 "a"            string str3 = "aa";                //expect: 2 "aa"            string str4 = "aba";            //expect: 3 "aba"            string str5 = "abcd";            //expect: 2 "ab"            string str6 = "abcdedcba";        //expect: 3 "ded"            string str7 = "abbcdededcba";    //expect: 5 "deded"            string str8 = "eceba";            //expect: 3 "ece"            string str9 = "abaece";            //expect: 3 "aba"            string str10 = "ababcd";        //expect: 4 "abab"            string str11 = "cababcd";        //expect: 4 "abab"            string str12 = "abcdefgabcdefg";//expect: 2 "ab"            string str13 = "ababababababab";//expect: 14 "ababababababab"            Console.WriteLine(maxSubStrWithNChars(str1, 2));            Console.WriteLine(maxSubStrWithNChars(str2, 2));            Console.WriteLine(maxSubStrWithNChars(str3, 2));            Console.WriteLine(maxSubStrWithNChars(str4, 2));            Console.WriteLine(maxSubStrWithNChars(str5, 2));            Console.WriteLine(maxSubStrWithNChars(str6, 2));            Console.WriteLine(maxSubStrWithNChars(str7, 2));            Console.WriteLine(maxSubStrWithNChars(str8, 2));            Console.WriteLine(maxSubStrWithNChars(str9, 2));            Console.WriteLine(maxSubStrWithNChars(str10, 2));            Console.WriteLine(maxSubStrWithNChars(str11, 2));            Console.WriteLine(maxSubStrWithNChars(str12, 2));            Console.WriteLine(maxSubStrWithNChars(str13, 2));        }    }}

0 0