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algorithm notes: leetcode#762 prime number of set bits in binary representation

admin 11月 12, 2020 0

Problem

Solution

Analysis

Python implementation

class :
    def countPrimeSetBits(self, L, R):
        """
        :type L: int
        :type R: int
        :rtype: int
        """
        prime_set = {2, 3, 5, 7, 11, 13, 17, 19}
        return sum(bin(n).count('1') in prime_set for n in range(L, R+1))

Java implementation

class  {
    public int countPrimeSetBits(int L, int R) {
        Set<Integer> prime_set = new HashSet<>(Arrays.asList(2, 3, 5, 7, 11, 13, 17, 19));
        int ans = 0;
        
        for(int n = L; n <= R; n++){
            if(prime_set.contains(Integer.bitCount(n))){
                ans ++;
            }
        }
        return ans;
    }
}

Time complexity

O(N).

Space complexity

O(1).

Links

762. Prime Number of Set Bits in Binary Representation
(中文版) 算法笔记: 力扣#762 二进制表示中质数个计算置位