一天一大 leet(最长公共前缀)难度:简单 DAY-15

输入: ["flower","flow","flight"]
输出: "fl"

输入: ["dog","racecar","car"]
输出: ""
解释: 输入不存在公共前缀。

/**
 * @param {string[]} strs
 * @return {string}
 */
var longestCommonPrefix = function (strs) {
  if (!strs.length) return ''
  let _resultNum = strs[0].length - 1
  for (let i = 1; i < strs.length; i++) {
    while (
      strs[i - 1].substring(0, _resultNum + 1) !==
      strs[i].substring(0, _resultNum + 1)
    ) {
      _resultNum--
    }
  }
  return strs[0].substring(0, _resultNum + 1) || ''
}

/**
 * @param {string[]} strs
 * @return {string}
 */
var longestCommonPrefix = function (strs) {
  if (strs == null || strs.length == 0) {
    return ''
  }
  var prefix = strs[0]
  var count = strs.length
  for (var i = 1; i < count; i++) {
    prefix = CommonPrefix(String(prefix), String(strs[i]))
    if (prefix.length == 0) {
      break
    }
  }
  return prefix

  function CommonPrefix(str1, str2) {
    var length = Math.min(str1.length, str2.length)
    var index = 0
    while (index < length && str1.charAt(index) == str2.charAt(index)) {
      index++
    }
    return str1.substring(0, index)
  }
}

/**
 * @param {string[]} strs
 * @return {string}
 */
var longestCommonPrefix = function (strs) {
  if (strs == null || strs.length == 0) {
    return ''
  }
  var length = String(strs[0]).length
  var count = strs.length
  for (var i = 0; i < length; i++) {
    var c = strs[0].charAt(i)
    for (var j = 1; j < count; j++) {
      if (i == strs[j].length || strs[j].charAt(i) != c) {
        return strs[0].substring(0, i)
      }
    }
  }
  return strs[0]
}

/**
 * @param {string[]} strs
 * @return {string}
 */
var longestCommonPrefix = function (strs) {
  var re = strs[0] ? strs[0] : ''
  for (var i = 1; i < strs.length; i++) {
    var regex = new RegExp('^' + re)
    while (!regex.test(strs[i]) && re.length) {
      re = re.slice(0, re.length - 1)
      regex = new RegExp('^' + re)
    }
  }
  return re
}