LeetCode 3. Longest Substring Without Repeating Characters

题目描述

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.

题目思路

• 思路一、参考

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        vector dict(256, -1);
        int len = s.size();
        int start = -1, maxstr = 0;
        
        for(int i=0; i < len; i++){
            if(dict[s[i]] > start){
                start = dict[s[i]];
            }
            dict[s[i]] = i;
            maxstr = max(maxstr, i-start);
        }
        return maxstr;
    }
};

总结展望