网上有些例子有问题，所以重新写了下 求字符串的最长不重复字串

标签：

假设有一个字符串“abcdebfgh”

那么最长不重复字串是"cdebfgh"，长度是7

若是：abcdbefbghijij

应输出：befbghij

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication10
{
    class Program
    {
        static void Main(string[] args)
        {

            string ss = "abcdbefbghijij";
            var list = ss.ToCharArray();
            int left = 0;
            int right = 0;
            GetLen(list, out left, out right);
            Console.WriteLine(ss.Substring(left, right - left + 1));
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="list"></param>
        /// <param name="left">right index from 0</param>
        /// <param name="right">right index from 0</param>
        /// <returns></returns>
        public static int GetLen(char[] list, out int left, out int right)
        {
            if (list == null || list.Length <= 0)
            {
                throw new Exception("the input list length is 0");
            }

            int len = list.Length;
            left = 0;
            right = 0;
            int maxLen = 0;
            int start = 0;
            int tempMaxLen = 0;
            Dictionary<char, int> cache = new Dictionary<char, int>();
                for (int i = 0; i < len; i++)
                {
                    if (!cache.Keys.Contains(list[i]) || cache[list[i]]==-1) //这个建不存在或者有建，但是值为-1，表明这个字符还没出现过.
                    {
                        tempMaxLen++;
                        cache.Add(list[i], i);
                    }
                    else
                    {
                        //there is duplicated char   abcdbefgh
                        if (tempMaxLen > maxLen)
                        {
                            maxLen = tempMaxLen;
                            left = start;
                            right = i - 1;
                        }

                        tempMaxLen = i - cache[list[i]];
                        for (int j = start; j < cache[list[i]]; j++) // 注意：网上好多例子是清楚这个cache里所有的，应该是错误的；仅仅应该清楚上次重复字符前面的字符。
                        {
                            cache[list[j]] = -1;
                        }

                        start = cache[list[i]] + 1;
                        cache[list[i]] = i;
                    }
                }

                if (tempMaxLen > maxLen)
                {
                    maxLen = tempMaxLen;
                    left = start;
                    right = len-1;
                }

                return maxLen;
        }
    }
}

网上有些例子有问题，所以重新写了下 求字符串的最长不重复字串

标签：

原文地址：http://blog.csdn.net/fyifei0558/article/details/51360881