Add problem: #3 Longest Substring Without Repeating Characters

Author: o-p

difficulty/medium/0003 Longest Substring Without Repeating Characters

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+../../problems/0003-longest-palindromic-substring

list/Blind Curated 75/02. Longest Substring Without Repeating Characters

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+../../problems/0003-longest-palindromic-substring/

problems/0003-longest-palindromic-substring/README.md

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+### 3. Longest Substring Without Repeating Characters
+
+https://leetcode.com/problems/longest-substring-without-repeating-characters/
+
+Given a string `s`, find the length of the __longest substring__ without repeating characters.

problems/0003-longest-palindromic-substring/longest-substring-without-repeating-characters.js

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+/**
+ * @param {string} s
+ * @return {number}
+ */
+const lengthOfLongestSubstring = function(s) {
+  /** @var int 當前 char 位置 （1 base) */
+  let pos = 0
+  /** @var int 總體最長不重複字串 */
+  let longest = 0
+  /** @var int 當前不重複最長字串 */
+  let currentLength = 0
+  /** @var Map 所有文字前一次出現的位置 */
+  const lastOccurs = new Map()
+
+  // 每個字母我們都記錄最後一次出現的位置
+  // - 如果兩次出現的距離小於當前段落長度: 刷新段落長度
+  // - 如果兩次出現的距離大於當前段落長度: 當前段落長度 + 1
+  // 找出最長段落
+  for (const char of s) {
+    const last = lastOccurs.get(char) || 0
+    const distance = (++pos - last)
+    currentLength = distance > currentLength ? currentLength + 1 : distance
+    longest = Math.max(longest, currentLength)
+    lastOccurs.set(char, pos)
+  }
+
+  return longest
+};
+
+export default lengthOfLongestSubstring

problems/0003-longest-palindromic-substring/longest-substring-without-repeating-characters.test.js

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+import lswrc from './longest-substring-without-repeating-characters'
+
+test.each`
+       s        | expected
+  ${'abcabcbb'} | ${3}
+  ${'bbbbb'}    | ${1}
+  ${'pwwkew'}   | ${3}
+  ${''}         | ${0}
+`('Longest substring: ($s)', ({ s, expected }) =>
+  expect(lswrc(s)).toBe(expected)
+)