leetcode Count and Say

Count and Say

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Question Solution 

The count-and-say sequence isthe sequence of integers beginning as follows:
1, 11, 21, 1211,111221, ...

1 isread off as "one 1" or 11.
11 isread off as "two 1s" or 21.
21 isread off as "one 2, then one
1" or 1211.

Given an integer n,generate the nth sequence.

Note: The sequence of integerswill be represented as a string.

 题意是输入n，要求输出第n个string，每个string由前面的string决定。

 

Ac代码之未修改（带main函数）：

#include<iostream>

#include<cstring>

#include<sstream>

using namespace std;

string say(string &s)

{

      stringstreamss;

      charbeg=s[0];

      intans=0;

      for(inti=0;i<=s.length();i++)

      {

           if(s[i]==beg)

           ans+=1;

           else{

                 ss<<ans<<beg;

                 beg=s[i];

                 ans=1;

           }

      }

      returnss.str();

}

string out(int n)

{

      strings;

      if(n<1)

      returns;

      else

      {

           s='1';

           for(inti=1;i<n;i++)

           {

                 s=say(s);

           }

      }

      returns;     

}

int main()

{

      intn;

      while(cin>>n)

      cout<<out(n)<<endl;

      return0;

}

本题题目简单，只是leetcode的形式比较不适应，当习惯了没有main的提交方式之后这种easy的题目还挺好做的。这里用到了stringsteam将int->string。