feat: add 014

Author: Blankj

README.md

@@ -11,6 +11,7 @@
 |8|[String to Integer (atoi)][008]|Math, String|
 |9|[Palindrome Number][009]|Math|
 |13|[Roman to Integer][013]|Math, String|
+|14|[Longest Common Prefix][014]|String|
 
 
 ## Medium
@@ -36,3 +37,4 @@
 [008]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/008/README.md
 [009]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/009/README.md
 [013]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/013/README.md
+[014]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/014/README.md

note/013/README.md

@@ -9,7 +9,7 @@ Input is guaranteed to be within the range from 1 to 3999.
 **Tags:** Math, String
 
 
-## 思路0
+## 思路
 
 题意是罗马数字转整型数，范围从1到3999，查看下百度百科的罗马数字介绍如下，
 

note/014/README.md

@@ -0,0 +1,28 @@
+# [Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix/)
+
+## Description
+
+Write a function to find the longest common prefix string amongst an array of strings.
+
+**Tags:** String
+
+
+## 思路
+
+题意是让你从字符串数组中找出公共前缀，我的想法是找出最短的那个字符串的长度`minLen`，然后在`0...minLen`的范围比较所有字符串，如果比较到有不同的字符，那么直接返回当前索引长度的字符串即可，否则最后返回最短的字符串即可。
+
+``` java
+public class Solution {
+    public String longestCommonPrefix(String[] strs) {
+        int len = strs.length;
+        if (len == 0) return "";
+        int minLen = 0x7fffffff;
+        for (String str : strs) minLen = Math.min(minLen, str.length());
+        for (int j = 0; j < minLen; ++j)
+            for (int i = 1; i < len; ++i)
+                if (strs[0].charAt(j) != strs[i].charAt(j))
+                    return strs[0].substring(0, j);
+        return strs[0].substring(0, minLen);
+    }
+}
+```

project/LeetCode/leetcode/src/main/java/com/blankj/easy/_014/Solution.java

@@ -0,0 +1,32 @@
+package com.blankj.easy._014;
+
+import java.util.Arrays;
+import java.util.HashMap;
+
+/**
+ * <pre>
+ *     author: Blankj
+ *     blog  : http://blankj.com
+ *     time  : 2017/04/21
+ *     desc  :
+ * </pre>
+ */
+
+public class Solution {
+    public String longestCommonPrefix(String[] strs) {
+        int len = strs.length;
+        if (len == 0) return "";
+        int minLen = 0x7fffffff;
+        for (String str : strs) minLen = Math.min(minLen, str.length());
+        for (int j = 0; j < minLen; ++j)
+            for (int i = 1; i < len; ++i)
+                if (strs[0].charAt(j) != strs[i].charAt(j))
+                    return strs[0].substring(0, j);
+        return strs[0].substring(0, minLen);
+    }
+
+    public static void main(String[] args) {
+        Solution solution = new Solution();
+        System.out.println(solution.longestCommonPrefix(new String[]{"abc", "abcd", "ab"}));
+    }
+}