Add solution 014

Author: yanglbme

README.md

@@ -7,8 +7,7 @@
   <a href="https://github.com/yanglbme/leetcode"><img src="https://img.shields.io/badge/Lang-Java%2FPython%2FJS%2FCPP%2FGo%2F...-blue.svg" alt="Language"></a>
 </p>
 
-<h2 align="center">LeetCode Solution</h2>
-
+## Introduction
 Complete solutions to Leetcode problems, updated daily.
 
 ## Solution List
@@ -20,6 +19,7 @@ Complete solutions to Leetcode problems, updated daily.
 | 001 | [Two Sum](https://github.com/yanglbme/leetcode/tree/master/solution/001.Two%20Sum) | `Array`, `Hash Table` |
 | 007 | [Reverse Integer](https://github.com/yanglbme/leetcode/tree/master/solution/007.Reverse%20Integer) | `Math` |
 | 013 | [Roman to Integer](https://github.com/yanglbme/leetcode/tree/master/solution/013.Roman%20to%20Integer) | `Math`, `String` |
+| 014 | [Longest Common Prefix](https://github.com/yanglbme/leetcode/tree/master/solution/014.Longest%20Common%20Prefix) | `String` |
 | 021 | [Merge Two Sorted Lists](https://github.com/yanglbme/leetcode/tree/master/solution/021.Merge%20Two%20Sorted%20Lists) | `Linked List` |
 | 053 | [Maximum Subarray](https://github.com/yanglbme/leetcode/tree/master/solution/053.Maximum%20Subarray) | `Array`, `Divide and Conquer`, `Dynamic Programming` |
 | 070 | [Climbing Stairs](https://github.com/yanglbme/leetcode/tree/master/solution/070.Climbing%20Stairs) | `Dynamic Programming` |

solution/014.Longest Common Prefix/README.md

@@ -0,0 +1,66 @@
+## 最长公共前缀
+### 题目描述
+
+编写一个函数来查找字符串数组中的最长公共前缀。
+
+如果不存在公共前缀，返回空字符串 ""。
+
+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。
+```
+
+说明:
+
+所有输入只包含小写字母 a-z 。
+
+### 解法
+取字符串数组第一个元素，遍历每一个字符，与其他每个字符串的对应位置字符做比较，如果不相等，退出循环，返回当前子串。
+
+注意：其他字符串的长度可能小于第一个字符串长度，所以要注意数组越界异常。
+
+```java
+class Solution {
+    public String longestCommonPrefix(String[] strs) {
+        if (strs == null || strs.length == 0) {
+            return "";
+        }
+        if (strs.length == 1) {
+            return strs[0];
+        }
+        
+        char[] chars = strs[0].toCharArray();
+        int i = 0;
+        boolean flag = true;
+        for (; i < chars.length; ++i) {
+            char ch = chars[i];
+            
+            for (int j = 1; j < strs.length; ++j) {
+                if (strs[j].length() <= i) {
+                    flag = false;
+                    break;
+                }
+                if (strs[j].charAt(i) != ch) {
+                    flag = false;
+                    break;
+                }
+                
+            }
+            if (!flag) {
+                break;
+            }
+        }
+        return strs[0].substring(0, i);
+        
+        
+    }
+}
+```

solution/014.Longest Common Prefix/Solution.java

@@ -0,0 +1,35 @@
+class Solution {
+    public String longestCommonPrefix(String[] strs) {
+        if (strs == null || strs.length == 0) {
+            return "";
+        }
+        if (strs.length == 1) {
+            return strs[0];
+        }
+        
+        char[] chars = strs[0].toCharArray();
+        int i = 0;
+        boolean flag = true;
+        for (; i < chars.length; ++i) {
+            char ch = chars[i];
+            
+            for (int j = 1; j < strs.length; ++j) {
+                if (strs[j].length() <= i) {
+                    flag = false;
+                    break;
+                }
+                if (strs[j].charAt(i) != ch) {
+                    flag = false;
+                    break;
+                }
+                
+            }
+            if (!flag) {
+                break;
+            }
+        }
+        return strs[0].substring(0, i);
+        
+        
+    }
+}