feat: ADD 038

Author: Blankj

README.md

@@ -8,23 +8,24 @@
 |:------------- |:------------- |:------------- |
 |1|[Two Sum][001]|Array, Hash Table|
 |7|[Reverse Integer][007]|Math|
-|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|
-|19|[Remove Nth Node From End of List][019]|Linked List, Two Pointers|
 |20|[Valid Parentheses][020]|Stack, String|
 |21|[Merge Two Sorted Lists][021]|Linked List|
 |26|[Remove Duplicates from Sorted Array][026]|Array, Two Pointers|
 |27|[Remove Element][027]|Array, Two Pointers|
 |28|[Implement strStr()][028]|Two Pointers, String|
+|38|[Count and Say][028]|String|
 
 
 ## Medium
 
 |#|Title|Tag|
 |:------------- |:------------- |:------------- |
 |2|Add Two Numbers|Linked List, Math|
+|8|[String to Integer (atoi)][008]|Math, String|
+|19|[Remove Nth Node From End of List][019]|Linked List, Two Pointers|
 
 
 ## Hard
@@ -50,3 +51,4 @@
 [026]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/026/README.md
 [027]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/027/README.md
 [028]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/028/README.md
+[038]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/038/README.md

note/038/README.md

@@ -0,0 +1,58 @@
+# [Count and Say][title]
+
+## Description
+
+The count-and-say sequence is the sequence of integers beginning as follows:
+
+`1, 11, 21, 1211, 111221, ...`
+
+`1` is read off as `"one 1"` or `11`.
+
+`11` is read off as `"two 1s"` or `21`.
+
+`21` is read off as `"one 2`, then `one 1"` or `1211`.
+
+Given an integer *n*, generate the *n*<sup>th</sup> sequence.
+
+Note: The sequence of integers will be represented as a string.
+
+**Tags:** String
+
+
+## 思路
+
+题意是数和说，根据如下序列`1, 11, 21, 1211, 111221, ...`，求第n个数，规则很简单,就是数和说，数就是数这个数数字有几个，说就是说这个数，所以`1`就是1个1：`11`,`11`就是有2个1：`21`，`21`就是1个2、1个1：`1211`，可想而知后面就是`111221`，思路的话就是按这个逻辑模拟出来即可。
+
+``` java
+public class Solution {
+    public String countAndSay(int n) {
+        String str = "1";
+        while (--n > 0) {
+            int times = 1;
+            StringBuilder sb = new StringBuilder();
+            char[] chars = str.toCharArray();
+            int len = chars.length;
+            for (int j = 1; j < len; j++) {
+                if (chars[j - 1] == chars[j]) {
+                    times++;
+                } else {
+                    sb.append(times).append(chars[j - 1]);
+                    times = 1;
+                }
+            }
+            str = sb.append(times).append(chars[len - 1]).toString();
+        }
+        return str;
+    }
+}
+```
+
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我GitHub上的LeetCode题解：[awesome-java-leetcode][ajl]
+
+
+
+[title]: https://leetcode.com/problems/count-and-say
+[ajl]: https://github.com/Blankj/awesome-java-leetcode

project/LeetCode/leetcode/src/main/java/com/blankj/easy/_038/Solution.java

@@ -0,0 +1,39 @@
+package com.blankj.easy._038;
+
+/**
+ * <pre>
+ *     author: Blankj
+ *     blog  : http://blankj.com
+ *     time  : 2017/04/21
+ *     desc  :
+ * </pre>
+ */
+
+public class Solution {
+    public String countAndSay(int n) {
+        String str = "1";
+        while (--n > 0) {
+            int times = 1;
+            StringBuilder sb = new StringBuilder();
+            char[] chars = str.toCharArray();
+            int len = chars.length;
+            for (int j = 1; j < len; j++) {
+                if (chars[j - 1] == chars[j]) {
+                    times++;
+                } else {
+                    sb.append(times).append(chars[j - 1]);
+                    times = 1;
+                }
+            }
+            str = sb.append(times).append(chars[len - 1]).toString();
+        }
+        return str;
+    }
+
+    public static void main(String[] args) {
+        Solution solution = new Solution();
+        for (int i = 1; i < 6; i++) {
+            System.out.println(solution.countAndSay(i));
+        }
+    }
+}