leetcode14：最长公共前缀 ​

示例 1:

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

示例 2:

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

var a = 'flow';
var b = 'fleet';

function getCommon(a, b) {
  let result = '';
  let counter = 0;
  for (let i = 0; i < a.length; i++) {
      if (a[i] === b[i]) {
          result += a[i];
      }
  }
  return result
}

function maxPrefix (strs) {
  if (!strs || !strs.length) {
    return '';
  }

  // 从0开始依次比较
  let currentIndex = 0;

  while (true) {
    // 取第一个字符串的当前位字符作为参照
    const refer = strs[0][currentIndex];
    // 是否全部匹配
    const currentAllMatch = strs.reduce((pre, str) => {
      return pre && str.charAt(currentIndex) === refer;
    }, true);

    if (currentAllMatch) {
      currentIndex ++;
    } else {
      break;
    }
  }

  return strs[0].substring(0, currentIndex);
}