Python 解leetcode:3. Longest Substring Without Repeating Characters

  • 题目描述:求一个字符串的不含重复字符的最长连续子串的长度;
  • 思路:
  1. 使用一个哈希表保存字符出现的位置;
  2. 使用left和right分别表示子串的最左和最右字符的下标;
  3. 遍历字符串,如果当前字符在哈希表中并且当前字符在哈希中的位置大于left,表明left和right之间存在和right索引上相同的字符,此时把left置为当前值在哈希表中的值;
  4. 把当前索引值+1,表示是第几个字符,求出当前最大长度;
  5. 3-4步重复,直到获得遍历完成;

感觉这是个动态规划题,暂时没用动态规划分析,后续再说。

class Solution(object):
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        hashes = {}
        left, right, length = 0, 0, len(s)
        max_len = 0
        while right < length:
            if hashes.get(s[right]) and hashes[s[right]] >= left:
                left = hashes[s[right]]
            hashes[s[right]] = right + 1
            max_len = max(max_len, right - left + 1)
            right += 1
        return max_len 
时间: 2024-10-09 12:38:43

Python 解leetcode:3. Longest Substring Without Repeating Characters的相关文章

【leetcode】 Longest Substring Without Repeating Characters

题目: 给定一个字符串,返回该串没有重复字符的最长子串. 分析: 1)子串:子串要求是连续的. 2)无重复,出现重复就断了,必须从新的位置开始.而新的位置就是重复字符第一次出现位置的下一个位置. 3)整个串可能没有一处重复. 那么,为了找出当前访问的字符是否出现过,要怎么做呢?当然是hash,O(1)的时间,而且既然是字符, 定义个255的hash table 就可以了,hash table 中的元素为相应字符在s中出现的位置.初始化为-1,表示都没有出现. 我们另外定义一个start 和end

leetcode -day21 Longest Substring Without Repeating Characters

 1.Longest Substring Without Repeating Characters 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

[LeetCode] 5. Longest Substring Without Repeating Characters 最长回文子串

[LeetCode] 5. Longest Substring Without Repeating Characters Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. Example 1: Input: "babad" Output: "bab" Note: "aba&qu

leetcode 3. Longest Substring Without Repeating Characters (Python版)

题目: 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 s

[LeetCode]3. Longest Substring Without Repeating Characters寻找最长无重复字符的子串

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 subst

[LeetCode][JavaScript]Longest Substring Without Repeating Characters

Longest Substring Without Repeating Characters 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 lengt

Leetcode 3 Longest Substring Without Repeating Characters. (最长无重复字符子串) (滑动窗口, 双指针)

目录 问题描述 例子 方法 Leetcode 3 问题描述 Given a string, find the length of the longest substring without repeating characters. 例子 Example 1: Input: "abcabcbb" Output: 3 Explanation: The answer is "abc", with the length of 3. Example 2: Input: &q

[LeetCode] 3. Longest Substring Without Repeating Characters

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.

Leetcode 03 Longest Substring Without Repeating Characters

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 subst

Java for LeetCode 003 Longest Substring Without Repeating Characters

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 subst