Number of Substrings Containing All Three Characters

class Solution {
public:
int numberOfSubstrings(string s) {//NO OF SUBSTRINGS CONTAINING A B AND C ATLEAST ONCE 

    int a=0,b=0,c=0;//COUNTS OF A B AND C COULD ALSO USE A MAP NO PROBLEM 
    int n=s.size();
    int j=0,i=0;//2 POINTERS FOR THE WINDOW 
    int ans=0;//STORING COUNT OF SUCH SUBSTRING 
    while(j<n){
        if(s[j]=='a')a++;
        else if(s[j]=='b')b++;
        else c++;        //INCREASING COUNT OF A/B/C IN THE STRING         
        while(a>=1&&b>=1&&c>=1){//IF A B AND C OCCUR AT LEAST ONCE AS IS THE CONDIITON IN THE QUESTION
                ans+=n-j;//THEN N-J ADDED THAT IS IF ANY OTHER UPCOMING CHARATCER IS ADDED IT STILL SATISFIES THE SUBSTIRNG CONDITION SO ANS+=N-J REMAING CHAR COUNT ADDED
                 if(s[i]=='a')a--;//IF FRONT PART OF WINDOW A DECREASE
                 else if(s[i]=='b')b--;//B THEN DECREASE
                 else c--;//SAME FOR C 
                 i++;//NOW OPS EXCLUDED NOW SLIDE THE WINDOW BY I++
            }//END OF WHILE LOOP
        j++;//J TOH ALWAYS INCREASES 
    }
    return ans;//FINALLY RETURN ANS 
}
};