Preface Numbering

链接

分析：先打表需要用到的罗马数字，然后暴力转换，最后统计一下即可

 /*
     PROB:preface
     ID:wanghan
     LANG:C++
 */
 #include "iostream"
 #include "cstdio"
 #include "cstring"
 #include "string"
 #include "map"
 using namespace std;
 const int maxn=;
 char s[]={'I','V','X','L','C','D','M'};
 int  h[]={,,,,,,,,,,,,,,,,,,,,,,,,,,,,,};
 int n;
 struct Node{
     int x;
     string str;
 };
 Node p[maxn];
 map<int,string> mp;
 void init(){
     mp[]="I",mp[]="II",mp[]="III",mp[]="IV",mp[]="V",mp[]="VI",mp[]="VII",mp[]="VIII",mp[]="IX";
     mp[]="X",mp[]="XX",mp[]="XXX",mp[]="XL",mp[]="L",mp[]="LX",mp[]="LXX",mp[]="LXXX",mp[]="XC";
     mp[]="C",mp[]="CC",mp[]="CCC",mp[]="CD",mp[]="D",mp[]="DC",mp[]="DCC",mp[]="DCCC",mp[]="CM";
     mp[]="M",mp[]="MM",mp[]="MMM";
 }
 string solve(int num){
     string res="";
     while(num){
         int pos=-;
         for(int i=;i>=;i--){
             if(num>=h[i]){
                 pos=i; break;
             }
         }
         int mod=num/h[pos];
         for(int i=;i<=mod;i++){
             num-=h[pos];
             res+=mp[h[pos]];
         }
         //num-=h[pos];
         //res+=mp[h[pos]];
     }
     return res;
 }
 map<char,int>mr;
 int main()
 {
     freopen("preface.in","r",stdin);
     freopen("preface.out","w",stdout);
     cin>>n;
     init();
     for(int i=;i<=n;i++){
         p[i].x=i;
         p[i].str=solve(i);
         //cout<<i<<": ";
         //cout<<p[i].str<<endl;
     }
     for(int i=;i<=n;i++){
         for(int j=;j<p[i].str.length();j++){
             mr[p[i].str[j]]++;
         }
     }
     for(int i=;i<;i++){
         if(mr[s[i]]==)  continue;
         else{
             cout<<s[i]<<" "<<mr[s[i]]<<endl;
         }
     }
     return ;
 }