leetcode Longest Substring Without Repeating Characters 难度系数3 3.2

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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本文介绍了一种算法，用于解决字符串中无重复字符最长子串的问题，通过实例演示了如何实现并优化该算法。

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Question：

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.

public class Solution {
    public int lengthOfLongestSubstring(String s) {
		if (s == null || s.length() == 0) {
			return 0;
		}
		int max = 0;
		int start = 0;
		int[] lastindex = new int[26];
		Arrays.fill(lastindex, -1);
		for (int i = 0; i < s.length(); i++) {
			if (lastindex[s.charAt(i) - 'a'] >= start) {
				max = Math.max(i - start, max);
				start = lastindex[s.charAt(i) - 'a'] + 1;
			}
			lastindex[s.charAt(i) - 'a'] = i;
		}
		return Math.max(s.length()-start, max);

	}
}