[LeetCode]Longest Substring Without Repeating Characters

Longest Substring Without Repeating Characters

 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.

 

用一个256的数组记录每个char出现的位置，初始化为-1，当其不是-1时，说明该字符存在。

在一些例子上找规律，比如‘dvdf’为3，‘abb’为2，‘aab’为2，'aa'为1等。

找到每个子字符串大小的规律即可。

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        int result=0;
        int position[256];
        fill(position,position+256,-1);
        int len=0;
        for(int i=0;i<s.length();i++)
        {
            if(position[s[i]]>-1)
            {
                result = max(len,result);
                len=0;
                i=position[s[i]]+1;
                fill(position,position+256,-1);
            }
            len++;
            position[s[i]]=i;
        }
        result = max(len,result);
        return result;
    }
};