LeetCode 无重复字符的最长子串算法题解 All In One

js / ts 实现无重复字符的最长子串

无重复字符的最长子串原理图解

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"use strict";

/**
 *
 * @author xgqfrms
 * @license MIT
 * @copyright xgqfrms
 * @created 2022-09-30
 * @modified
 *
 * @description 3. 无重复字符的最长子串
 * @description 3. Longest Substring Without Repeating Characters
 * @difficulty Medium
 * @ime_complexity O(n)
 * @space_complexity O(1)
 * @augments
 * @example
 * @link https://leetcode.com/problems/longest-substring-without-repeating-characters/
 * @link https://leetcode-cn.com/problems/longest-substring-without-repeating-characters/
 * @solutions
 *
 * @best_solutions
 *
 */

export {
  lengthOfLongestSubstring,
};

const log = console.log;


function lengthOfLongestSubstring(str: string): number {
  let maxStr = ``;
  let maxLen = 0;
  for(const c of str) {
    let index = maxStr.indexOf(c);
    if(index > -1) {
      // slice + 1，截取当前字符后面的字符串
      // slice +1 从下一个字符开始截取
      maxStr = maxStr.slice(index + 1);
    }
    maxStr += c;
    if(maxLen < maxStr.length) {
      // 更新最长字符串
      maxLen = maxStr.length;
    }
    // maxLen = Math.max(maxLen, maxStr.length);
  }
  return maxLen;
}

function getMaxSubStr(str: string): string {
  let result = ``;
  let maxStr = ``;
  let maxLen = 0;
  for(const c of str) {
    let index = maxStr.indexOf(c);
    if(index > -1) {
      // slice + 1，截取当前字符后面的字符串
      maxStr = maxStr.slice(index + 1);
    }
    maxStr += c;
    if(maxLen < maxStr.length) {
      maxLen = maxStr.length;
      result = maxStr;
    }
  }
  return result;
}

function getMaxSubStrObj(str: string): Object {
  let result = ``;
  let maxStr = ``;
  let maxLen = 0;
  for(const c of str) {
    let index = maxStr.indexOf(c);
    if(index > -1) {
      // slice + 1，截取当前字符后面的字符串
      maxStr = maxStr.slice(index + 1);
    }
    maxStr += c;
    if(maxLen < maxStr.length) {
      maxLen = maxStr.length;
      result = maxStr;
    }
  }
  return {
    maxStr: result,
    maxLen
  };
}


/*

"abcabcbb"
"bbbbb"
"pwwkew"

*/

// 测试用例 test cases
const testCases = [
  {
    input: "abcabcbb",
    result: 3,
    desc: 'value equal to 3',
  },
  {
    input: "bbbbb",
    result: 1,
    desc: 'value equal to 1',
  },
  {
    input: "pwwkew",
    result: 3,
    desc: 'value equal to 3',
  },
];

for (const [i, testCase] of testCases.entries()) {
  const result = lengthOfLongestSubstring(testCase.input);
  log(`test case ${i} result: `, result === testCase.result ? `✅ passed` : `❌ failed`, result);
  // log(`test case i result: `, result === testCase.result ? `passed ✅` : `failed ❌`, result);
  // log(`test case i =`, testCase);
}


/*
$  npx ts-node ./003\ longest-substring-without-repeating-characters.ts

test case 0 result:  ✅ passed 3
test case 1 result:  ✅ passed 1
test case 2 result:  ✅ passed 3
*/

https://leetcode.com/problems/longest-substring-without-repeating-characters/

https://leetcode.cn/problems/longest-substring-without-repeating-characters/