CountandSay

Change-Id: Id9ecbf353e2b65df40a69708115d2672b1f14360

Author: applewjg

CountandSay.java

@@ -0,0 +1,45 @@
+/*
+ Author:     King, [email protected]
+ Date:       Dec 20, 2014
+ Problem:    Count and Say
+ Difficulty: Easy
+ Source:     https://oj.leetcode.com/problems/count-and-say/
+ Notes:
+ 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 nth sequence.
+ Note: The sequence of integers will be represented as a string.
+
+ Solution: ...
+*/
+
+ public class Solution {
+    public String countAndSay(int n) {
+        StringBuffer s = new StringBuffer("1");
+        StringBuffer res = new StringBuffer();
+        while((--n) != 0){
+            res.setLength(0);
+            int size = s.length();
+            int cnt = 1;
+            char cur = s.charAt(0);
+            for(int i=1;i<size;i++){
+                if(s.charAt(i)!=cur){
+                    res.append(cnt);
+                    res.append(cur);
+                    cur = s.charAt(i);
+                    cnt = 1;
+                }else ++cnt;
+            }
+            res.append(cnt);
+            res.append(cur);
+            StringBuffer tmp = s;
+            s = res;
+            res = tmp;
+        }
+        return s.toString();
+    }
+}