leetcode Longest Substring Without Repeating Characters

最新推荐文章于 2021-12-03 15:58:56 发布

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本文介绍了一种使用哈希表解决字符串问题的方法，通过跟踪字符出现的位置来找到最长的不包含重复字符的子字符串。这种方法能够高效地解决此类问题，并提供了一个具体的C++实现示例。

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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.

本质用哈希计算

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        if (s.empty()) return 0;
        char hash[260];
        memset(hash,0,sizeof hash);
		hash[s[0]] = 1;
        int max_len = 1;
        size_t len = s.size();
        string::iterator iter_first = s.begin();
        string::iterator last = s.begin();++last;
        
        for (;last != s.end();)
        {
            //hash has the s,so we should ++first and modify
            //max 
            if (hash[*last])
            {
				max_len = std::max(max_len,(int)distance(iter_first,last));
                while(*iter_first != *last)
				{
					hash[*iter_first] = 0;
					++iter_first;
				}
                ++iter_first;
            }
    
            hash[*last] = 1;
			++last;
        }
        
		max_len = std::max(max_len,(int)distance(iter_first,last));
        return max_len;
    }
};