【LeetCode】C# 3、Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters.

Examples:

Given “abcabcbb”, the answer is “abc”, which the length is 3.

Given “bbbbb”, the answer is “b”, with the length of 1.

Given “pwwkew”, the answer is “wke”, with the length of 3. Note that the answer must be a substring, “pwke” is a subsequence and not a substring.

这道题关键在于利用 BitArray来记录字母是否首次出现。时间复杂度O(n)

public class Solution {    public int LengthOfLongestSubstring(string s) {        int max = 0;        BitArray map = new BitArray(256,false);        int l = 0,r = 0;        int n = s.Length;        while (r<n){            if(map[s[r]]){                max = Math.Max(max,r-l);                while(s[l] != s[r]){                    map[s[l]] = false;                    l++;                }                l++;                r++;            }            else{                map[s[r]] = true;                r++;            }        }        max = Math.Max(max,r-l);        return max;    }}