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=4000;
char s[]={'I','V','X','L','C','D','M'};
int  h[]={1,2,3,4,5,6,7,8,9,10,20,30,40,50,60,70,80,90,100,200,300,400,500,600,700,800,900,1000,2000,3000};
int n;
struct Node{
    int x;
    string str;
};
Node p[maxn];
map<int,string> mp;
void init(){
    mp[1]="I",mp[2]="II",mp[3]="III",mp[4]="IV",mp[5]="V",mp[6]="VI",mp[7]="VII",mp[8]="VIII",mp[9]="IX";
    mp[10]="X",mp[20]="XX",mp[30]="XXX",mp[40]="XL",mp[50]="L",mp[60]="LX",mp[70]="LXX",mp[80]="LXXX",mp[90]="XC";
    mp[100]="C",mp[200]="CC",mp[300]="CCC",mp[400]="CD",mp[500]="D",mp[600]="DC",mp[700]="DCC",mp[800]="DCCC",mp[900]="CM";
    mp[1000]="M",mp[2000]="MM",mp[3000]="MMM";
}
string solve(int num){
    string res="";
    while(num){
        int pos=-1;
        for(int i=29;i>=0;i--){
            if(num>=h[i]){
                pos=i; break;
            }
        }
        int mod=num/h[pos];
        for(int i=1;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=1;i<=n;i++){
        p[i].x=i;
        p[i].str=solve(i);
        //cout<<i<<": ";
        //cout<<p[i].str<<endl;
    }
    for(int i=1;i<=n;i++){
        for(int j=0;j<p[i].str.length();j++){
            mr[p[i].str[j]]++;
        }
    }
    for(int i=0;i<7;i++){
        if(mr[s[i]]==0)  continue;
        else{
            cout<<s[i]<<" "<<mr[s[i]]<<endl;
        }
    }
    return 0;
}