LeetCode 3. Longest substring without duplicate characters

Hi, Hello everyone , I am Xiaozhuang .

Today's algorithm for punching cards is —— Power button 3. Longest substring without repeating characters

This question is a school call + Social recruitment , Check the algorithm problem with the second highest frequency , The frequency ranking first is the reverse linked list , See the previous article in the official account for a detailed solution .

This question will use 「 Hashtable + The sliding window 」 Realization , Don't talk much , Let's study together ～

One 、Leetcode subject

1、 Title address

Click to see Leetcode subject

2、 Specific topic

Two 、 Implementation code

1、 Ideas ： Hashtable + The sliding window

（1） Specific code

/**
 * @param {string} s
 * @return {number}
 */
//   Hashtable  +  The sliding window 
//  Time complexity : O(n),n For the string s The length of 
//  Spatial complexity : O(n), n by map The length of 
var lengthOfLongestSubstring = function(s) {
    let map = new Map();
    let start = 0;
    let end = 0;
    let max = 0;
    while(true) {
        if(end >= s.length) {
            break;
        }
        let temp = map.get(s[end]);
        //map Does not exist in 
        if(temp === undefined || temp < start) {
            max = Math.max(max, end - start + 1);
        }else {//map There is already 
            start = temp + 1;
        }
        map.set(s[end], end);
        end++;
    }
    return max;
};

（2） Running results

3、 ... and 、 Explain the video

Click to see B The station explains the video

Four 、 The supplementary part

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