0014. Longest Common Prefix (E)

Longest Common Prefix (E)

题目

Write a function to find the longest common prefix string amongst an array of strings.

If there is no common prefix, return an empty string "".

Example 1:

Input: ["flower","flow","flight"]
Output: "fl"

Example 2:

Input: ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.

Note:

All given inputs are in lowercase letters a-z.

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题意

找到给定字符串组的公共前缀。

思路

以第一个字符串中的字符为基准，再去比对其余字符串中对应位置处的字符。

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代码实现

Java

class Solution {
    public String longestCommonPrefix(String[] strs) {
        if (strs == null || strs.length == 0) {
            return "";
        }
        String ans = "";
        for (int i = 0; i < strs[0].length(); i++) {
            char c = strs[0].charAt(i);
            for (int j = 1; j < strs.length; j++) {
                if (i == strs[j].length() || strs[j].charAt(i) != c) {
                    return ans;
                }
            }
            ans += c;
        }
        return ans;
    }
}

JavaScript

/**
 * @param {string[]} strs
 * @return {string}
 */
var longestCommonPrefix = function (strs) {
  if (strs.length === 0) {
    return ''
  }

  let prefix = ''

  for (let i = 0; i < strs[0].length; i++) {
    let c = strs[0][i]
    for (let j = 1; j < strs.length; j++) {
      if (i === strs[j].length || strs[j][i] !== c) {
        return prefix
      }
    }
    prefix += c
  }

  return prefix
}