Longest Substring JavaScript - LeetCode Solution

longest-substring.js

// 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.

// Given "pwwkew", 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.




var lengthOfLongestSubstring = function(s) {
    
    let map = {}
    let start = 0
    let maxLen = 0
    let arr = s.split('')
    
    for (i=0; i < s.length; i++) {
        let current = map[arr[i]]
        if (current!=null && start <= current) {
            start = current + 1
        } else {
            maxLen = Math.max(maxLen, i - start + 1)
        }
        
        map[arr[i]] = i
    }
    
    return maxLen
    
    
};

function getLongestSubString(str) {
  if(!str.trim()) {
    return "Please enter string";
  }
  const strArray = str.trim().split('');
  let count = 0, maxLength = 0, index;
  for(let i = 0; i<strArray.length; i++) {
    if(strArray[i] === strArray[i+1]) {
      count++;
    } else {
      if(count> maxLength) {
        maxLength = count;
        index=i;
      } 
      count=0;
    }
  }
  
  const subStrIndex = index - maxLength;
  const subString = str.slice(subStrIndex, subStrIndex + maxLength+1)
  
  if(subString) {
    return {index: subStrIndex, length: maxLength + 1, subString: subString };
  }
  
  return "No sub-string found";
}

const str = "aabbbcd";
console.log(largestSubString(str)) // {index: 2, length: 3, subString: "bbb", }

function maxSubstring(s) {
  // Write your code here
  const array = []
  const lengthS = s.length
  const pusher = (value) => {
    if (value !== '') {
      if (array.length > 0) {
        if (array.indexOf(value) === -1) {
          array.push(value)
        }
      } else {
        array.push(value)
      }
    }
  }
  pusher(s)
  for (const [index, value] of s.split('').entries()) {
    let length = lengthS
    let string = s
    const indexO = s.indexOf(value)
    pusher(value)
    while (length > indexO) {
      pusher(string.slice(index-1, length + 1))
      length = --length
    }
    string = s.slice(index, lengthS)
  }
  array.sort()
  return array.pop()
}

let str = "abcabcbbb";
let seen = {};
let start = 0;
let maxLength = 0;

[...str].map((itm, i) => {
if(itm in seen && start <= seen[itm]) {
start = seen[itm];
maxLength = Math.max(i - start, maxLength)
}
seen[itm] = i
})

console.log(maxLength)