utopiantree.cpp

int utopianTree(int n) {
    int res = 0;
    int rem = 0;
    for(int i = 0; i <= n; i++){
        if(rem == 0 && i > 0){
            res = res * 2;
        }else{
            res = res + 1;
        }
        int mod = i % 2;
        rem = mod;
    }
    return res;
}