알고리즘 기초 다지기 프로젝트 (feat. 코드없는 프로그래밍) [2021년 06월 02일]

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Leetcode - Longest Substring Without Repeating Characters

문제: LeetCode - 3. Longest Substring Without Repeating Characters

코드

• 코드 (1) : 통과 성공

/**
   * @param {string} s
   * @return {number}
   */
const lengthOfLongestSubstring = (s) => {
  // 'abcdeca' -> 5
  // "pwwkew" -> 3 (4)
  const alphaMap = createAlphaMap(s);
  let maxLength = 0;
  let begin = 0,
    finish = 0;

  while (finish < s.length) {
    const currChar = s[finish];

    const beginNextIdx = alphaMap[currChar] + 1;
    if (begin + 1 <= beginNextIdx) begin = beginNextIdx;

    const tmpLength = finish - begin + 1;
    maxLength = Math.max(tmpLength, maxLength);
    alphaMap[currChar] = finish;

    finish++;
  }
  return maxLength;
};

lengthOfLongestSubstring('pwwkew');

// --
const createAlphaMap = () => {
  const result = {};
  const nStartLowerCase = 97;
  const alphaRange = 25;
  const max = nStartLowerCase + alphaRange;
  for (let i = nStartLowerCase; i <= max; i++) {
    const alpha = String.fromCharCode(i);
    result[alpha] = -1;
  }
  return result;
};

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참고 자료

강의

• 코딩테스트, 중급, Longest substring w/o Repeats