View Code of Problem 101

#include<bits/stdc++.h>
using namespace std;

int main(){
    char s[100],a[100]={0};
    while(gets(s)){
    	int k=0,count=0;
    	for(int i = strlen(s)-1; i >= 0; i--){
    		if(s[i]!=','){
    			a[k] = s[i];
    			k++;
    			count++;
    			if(count==3&&i!=0){
					a[k] = ',';
					k++;
					count = 0; 
				}
			}
		}
		for(int i = k-1; i >= 0; i--){
			cout<<a[i];
		}
		cout<<endl;
	}
}