LeetCode #3 Longest Substring Without Repeating Characters C# Solution

LeetCode #3 Problem

Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for “abcabcbb” is “abc”, which the length is 3. For “bbbbb” the longest substring is “b”, with the length of 1.

记录目前考察的子串的开头和结尾，出现过的字母、出现过的子串的字母的位置。

从头到尾扫这个数组，每往后扫一位，如果pos位置上的字母出现过，那就吧start移动到上一个这个字母出现的位置同时end++；如果没出现过那就end++。

第一次提交的时候以为这个字符串只有字母，WA了一次……看到测试数据的我是崩溃的……

C# Code
public class Solution
{
public int LengthOfLongestSubstring(string s)
{
int start = 0, end = 0;
bool[] exist = new bool[300];
int[] position = new int[300];
for (int i = 0; i < 200; i++)
{
exist[i] = false;
position[i] = 0;
}
for (int i = 0; i < s.Length; i++)
{
if (exist[s[i]] == true)
{
for (int j = start; j <= position[s[i]]; j++) exist[s[j]] = false;
start = position[s[i]] + 1;
exist[s[i]] = true;
position[s[i]] = i;
}
else
{
exist[s[i]] = true;
position[s[i]] = i;
if (end <= i - start + 1) end = i - start + 1;
}
}
return end;
}
}