3. Longest Substring Without Repeating Characters

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最新推荐文章于 2024-01-06 13:50:14 发布

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本文介绍了一种解决最长无重复字符子串问题的方法，并提供了一个使用Java实现的具体示例。该方法通过滑动窗口的方式遍历字符串，利用哈希表记录字符出现的位置，从而高效地找出最长无重复字符子串的长度。

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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.

import java.util.HashMap;

class Solution {
    public int lengthOfLongestSubstring(String s) {
        
        char [] strarr=s.toCharArray();
        HashMap<Character,Integer> m=new HashMap<Character,Integer>();
        int res=0;
        for(int i=0,j=0;i<strarr.length;i++)
        {
            if(m.containsKey(strarr[i]))
            {
                 j=Math.max(m.get(strarr[i]),j);
            }
            res=Math.max(res,i-j+1);
            m.put(strarr[i],i+1);
        }
        
        return res;
    }
}