LeetCode | 3. Longest Substring Without Repeating Characters

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本文详细解析了寻找字符串中最长无重复字符子串的算法实现，通过具体示例展示了如何利用unordered_map数据结构来高效解决问题。文章通过三个实例说明了算法的正确性和效率，适合对字符串操作和数据结构感兴趣的读者。

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题目：

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

Example 1:

Input: "abcabcbb"
Output: 3 
Explanation: The answer is "abc", with the length of 3.

Example 2:

Input: "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.

Example 3:

Input: "pwwkew"
Output: 3
Explanation: 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.

代码：

#include<unordered_set>

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        int maxlen = 0;
		for (int i = 0; i < s.size(); i++)
		{
			unordered_map<char, int> letters;
			int j;
			for (j = i; j < s.size(); j++)
			{
				letters[s[j]]++;
				if (letters[s[j]] > 1)
					break;
			}
			if (j - i > maxlen)
				maxlen = j - i;
		}
		return maxlen;
    }
};