14. Longest Common Prefix

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.
难度：easy
题目：写方法从一字符串数组中找出最长公共前缀, 如果没则返回空字符串。所有给出的输入字符串都由小写字母组成。
Runtime: 5 ms, faster than 79.60% of Java online submissions for Longest Common Prefix.
public class Solution {
public String longestCommonPrefix(String[] strs) {
if (strs.length < 1) {
return “”;
}

int minStrLen = strs[0].length(), minIdx = 0;
for (int i = 0; i < strs.length; i++) {
if (minStrLen > strs[i].length()) {
minStrLen = strs[i].length();
minIdx = i;
}
}
String prefix = strs[minIdx];
for (int i = 0; i < strs.length; i++) {
for (int j = 0; j < prefix.length() && j < strs[i].length(); j++) {
if (prefix.charAt(j) != strs[i].charAt(j)) {
prefix = prefix.substring(0, j);
break;
}
}
}

return prefix;
}
}