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Solving LeetCode - Longest Substring Without Repeating Characters

phariale profile image pharia-le ・1 min read

Question

Given a string s, find the length of the longest substring without repeating characters.

Example 1:

Input: s = "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3.
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Example 2:

Input: s = "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.
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Example 3:

Input: s = "pwwkew"
Output: 3
Explanation: The answer is "wke", with the length of 3.
Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.
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Example 4:

Input: s = ""
Output: 0
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Constraints:

  • 0 <= s.length <= 5 * 104
  • s consists of English letters, digits, symbols and spaces.

Let's Go!

Solve by using PREP.

  • P - A string s of letters, digits, symbols and spaces
  • R - Return a number which is the length of the Longest Substring Without Repeating Characters
  • E - Examples provided by question. (See Above)
  • P - See Below

Attempt 1

var lengthOfLongestSubstring = function(s) {
    const arr = s.split('')
    let charMap = {}
    let count = [ 0 ]

    for (let i=0; i<arr.length; i++) {
        if (!charMap[arr[i]]) {
            count[count.length - 1] = count[count.length - 1]+1
            charMap[arr[i]] = 1
        } else {
            charMap = {}
            charMap[arr[i]] = 1
            count[count.length] = 1
        }
    }
    return count.reduce((max, current) => current > max ? current : max)
};

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Results of Attempt 1

console.log(lengthOfLongestSubstring("abcabcbb")) // 3 - PASS
console.log(lengthOfLongestSubstring("aab")) // 2 - PASS
console.log(lengthOfLongestSubstring("dvdf")) // 2  - FAIL (CORRECT is 3) 
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To Be Continued...

Attempt 2...

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