CODEWITHSUNDEEP
c++if-statement
Brothers on the Road
Brothers on the Road

Reputation: 3

C++ multiple nested If-else statements work but combined doesn't

I'm a newbie to c++. I attempted a questions related to bitsets(https://www.codechef.com/problems/CHEFQUE), when I use the following nested statements the code passes all the tests

    for(int i=1;i<Q+1;i++){
        temp = S/2;
        if(S&1){ //odd
            if(!sets[temp]){
                sets[temp] = true;
                sum+=temp;
            }
        }
        else{    //even
            if(sets[temp]){
                sets[temp] = false;
                sum-=temp;
            }
        }
        S = (A*S + B);

But when I combine the multiple if-else statements, it fails on some tests

    for(int i=1;i<Q+1;i++){
        temp = S/2;
        if(S&1 && !sets[temp]){ //odd and empty
            sets[temp] = true;
            sum+=temp;
        }
        else if(!S&1 && sets[temp]){    //even ond occupied
            sets[temp] = false;
            sum-=temp;
        }
        S = (A*S + B);
    }

I really have no clue why this would happen, I'm sure it must be really stupid. I would really be thankful if someone helped.

Upvotes: 0

Views: 71

Answers (1)

Alberto
Alberto

Reputation: 12909

As you can see from this table the operator ! has a higher precedence that & (Bitwise and, not address of), so your code should looks like this:

    for(int i=1;i<Q+1;i++){
    temp = S/2;
    if(S&1 && !sets[temp]){ //odd and empty
        sets[temp] = true;
        sum+=temp;
    }
    else if(!(S&1) && sets[temp]){    //even ond occupied
        sets[temp] = false;
        sum-=temp;
    }
    S = (A*S + B);
}

Upvotes: 1

Related Questions