View Code of Problem 101

#include <iostream>
#include <cstdio>
#include <cstring>
#include <iomanip>
using namespace std;
int main(){
    char a[999],b[999],c[999];
    int t=0,j = 0,m = 0;
    while(cin.getline(a,999)){
        t = 0,m = 0,j = 0;
        for(long int i=0;i<strlen(a);i++){
            if(a[i]!=','){
                b[t]=a[i];
                t++;
            }
        }
        for(long int i=strlen(b)-1;i>=0;i--){
            if(m%3==0&&m!=0){
                c[j++]=',';
                
            }
                c[j++] = b[i];
                m++;
            b[i]=NULL;
        }
        for(int i=j-1;i>=0;i--){
            cout<<c[i];
            c[i]=NULL;
        }
        cout<<endl;
    }

    return 0;
}