LeetCode 3. Longest Substring Without Repeating Characters (双指针扫描的典型例题)

最新推荐文章于 2025-05-18 01:04:12 发布

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最新推荐文章于 2025-05-18 01:04:12 发布

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本文详细解析了如何使用双指针法求解最长无重复子串的问题，通过具体的代码实现展示了算法的运行过程。文章包含多个示例，帮助读者理解算法原理。

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3. Longest Substring Without Repeating Characters

Medium

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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.

题意：给你一个字符串，求最长不重复子串的长度。

题解：双指针扫描

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        map<char,int> mp;
        mp.clear();
        int begin = 0;
        int end = 0;
        int l = 0;
        int r = 0;
        int Max = 0;
        while(end < s.size()){
            mp[s[end]]++;
            if(mp[s[end]] > 1){
                while(begin <= end && mp[s[end]] > 1){
                    mp[s[begin]]--;
                    begin++;
                }
            }
            if((end - begin + 1) > Max){
                Max = (end - begin + 1);
                l = begin;
                r = end;
            }
            end++;
        }
        return Max;
    }
};