dsa-competitive-programming/leetcode/lc762.cpp

class Solution{
    public:
        int countPrimeSetBits(int left, int right){
            int ans = 0;
            for(int i = left;i<=right;i++){
                if(isPrime(__builtin_popcount(i)))
                    ans++;
            }
            return ans;
        }
        bool isPrime(int n){
            if(n<2) return false;
            for(int i =2;i*i<=n;i++)
                if(n%i == 0) return false;
            return true;
        }
};
//TC : o(right-left+1)
//SC : o(1)

/*
int countPrimeSetBits(int L, int R) {
        int cnt = 0, hash[20] = {0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1};
        for (int i = L; i <= R; i++) {
            bitset<20> b(i);
            if(hash[b.count()]) cnt++;
        }
        return cnt;
    }
    */