我练习的代码如下：
#include<iostream>
using namespace std;
#include<vector>
#include<map>
map<int,int>mp;
vector<int> v;
vector<int>::iterator v1;
int main()
{
   int n,m,i,j,k,t;
   cin >>t;
   while(t--)
   {
      mp.clear();
      v.clear();   
       cin >> m;
       if(m ==1||m==-1)
       {cout<<m<<endl;continue;}
       if(m<0)
       {cout<<'-';m = -m;}
      cout<<"0.";
     n = 1; j = 0;
     while(n<m){n *= 10;j++;}
     for(int x = 1; x < j; x++)
        cout<<'0';
         while(1)
         {
          k = n/m;
          n %= m;
          if(mp.find(n) != mp.end())
          {if(mp[n] != k)
          v.push_back(k);
          break;}
          v.push_back(k);
          if(n == 0) break;
          mp[n] = k;
          n *= 10; j = 0;
          while(n<m){n*=10;j++;}
          for(int x =0; x < j; x++)
            v.push_back(0);
         }  
         for(v1 = v.begin(); v1 != v.end();v1++)
          cout<<*v1;
          cout<<endl;
   }
}但是每回提交都WA 到底哪错了呢？请高手指教。