LeetCode #3. Longest Substring Without Repeating Characters

lengthOfLongestSubstring.js

/**
 * @param {string} s
 * @return {number}
 */
var lengthOfLongestSubstring = function(s) {
    let result = 0,
        str = '';
    
    for(let i = 0; i < s.length; i++){        
        let c = s[i],
            j = str.indexOf(c);//重覆的位置
        
        if(j != -1){
            if(str.length > result){
                result = str.length;
            }
            //剩餘長度不足提前結束
            if(s.length - 1 - j < result){
                break;
            }
            
            str = str.substr(j + 1);//重覆字元後面的字串
        }         
        
        str += c;
    }
    
    if(str.length > result){
        return str.length;
    }
        
    return result;
};