与字符串相关的常见算法

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字符串逆序输出

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/*
 * @Description: reverseString
 * @Author: libk
 * @Github: <https://github.com/libk>
 */
function reverseString (str) {
  return str.split('').reverse().join('')
}

统计字符串中出现最多的字符及出现的次数

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/*
 * @Description: 统计字符串中出现最多的字符及出现的次数，出现次数最多的字符只有一个
 * @Author: libk
 * @Github: <https://github.com/libk>
 */
function getMaxCount (str) {
  const hashTable = {}
  for (let i = 0; i < str.length; i++) {
    if (hashTable[str[i]] === undefined) {
      hashTable[str[i]] = 1
    } else {
      hashTable[str[i]]++
    }
  }

  let maxCount = 0
  let maxChar = ''

  for (let i in hashTable) {
    if (hashTable[i] > maxCount) {
      maxCount = hashTable[i]
      maxChar = i
    }
  }
  return `字符${maxChar}出现次数最多，出现了${maxCount}次`
}

去除字符串中重复的字符

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/*
 * @Description: 字符串去重
 * @Author: libk
 * @Github: <https://github.com/libk>
 */
function removeDupChar (str) {
  const hashTable = {}
  let result = ''
  for (let i = 0; i < str.length; i++) {
    if (hashTable[str[i]] === undefined) {
      hashTable[str[i]] = true
      result += str[i]
    }
  }
  return result
}

判断一个字符串是否为回文字符串

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/*
 * @Description: 判断字符串是否为回文字符串，不区分大小写
 * @Author: libk
 * @Github: https://github.com/libk
 */
function isPalStr (str) {
  let start = 0
  let end = str.length - 1
  while (start < end) {
    if (str[start] === str[end]) {
      start++
      end--
    } else {
      return false
    }
  }
  return true
}