The count-and-say sequence is the sequence of integers with the first five terms as following:
1. 1
2. 11
3. 21
4. 1211
5. 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 term of the count-and-say sequence.
Note: Each term of the sequence of integers will be represented as a string.
Example 1:
Input: 1
Output: "1"
Example 2:
Input: 4
Output: "1211"
思路：
這道題是第i+1個(gè)字符串是第i個(gè)字符串的讀法。比如第4個(gè)字符串是1211背镇，它的讀法是1個(gè)1坪仇，1個(gè)2,2個(gè)1，因此第5個(gè)字符串是111221
var countAndSay = function(n) {
if(n<=0) return "";
var res='1';
for(var i=0;i<n-1;i++){
var cur="";
for(var j=0;j<res.length;++j){
var count=1;
while(j+1<res.length && res[j]==res[j+1]){
++count;
++j;
}
cur+=count+res[j]
}
res=cur;
}
return res;
};
