## Problem

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 *n*^{th} term of the count-and-say sequence.

Note: Each term of the sequence of integers will be represented as a string.

**Example 1:**

Input:1Output:"1"

**Example 2:**

Input:4Output:"1211"

## Analysis

This problem is about string operation

## Solution

class Solution { public: string countAndSay(int n) { string num = "1"; //interatively read n times for(int i=1; i<n; i++){ num = helper(num); } return num; } //helper function for reading a number string helper(string num){ stringstream nextStr; char last = num[0]; int count = 1; for(int i=1; i<num.size(); i++){ if(num[i] == last){ count++; }else{ nextStr<<count<<last; last = num[i]; count = 1; } } nextStr<<count<<last; return nextStr.str(); } };