2. single digit statistics

#include<iostream>
using namespace std;
#include<string>
#include<cstring>
int main()
{
    string s;
    getline(cin,s);
    int num[10];
    memset(num,0,sizeof(num));
    for(int i=0;i<s.size();i++)
    {
        char c=s[i];
        int n=c-'0';
        num[n]++;
    }
    for(int i=0;i<10;i++)
    {
        if(num[i])
        {
            printf("%d:%d\n",i,num[i]);
        }
    }
    return 0;
}

---

#include<iostream>
using namespace std;
#include<map>
int main()
{
    char c;
    map<int,int>mp;
    while((c=getchar())!='\n')
        mp[c-'0']++;
    for(map<int,int>::iterator it=mp.begin();it!=mp.end();it++)
    {
        cout<<it->first<<":"<<it->second<<endl;
    }
    return 0;
}