JZ-011-Number of 1 in binary

Number of 1s in binary

Title description

Enter an integer and output the number of 1s in the 32-bit binary representation of the number. The negative number is represented by one's complement.

title link : the number of 1 in binary

Code

/**
 * 标题：二进制中 1 的个数
 * 题目描述
 * 输入一个整数，输出该数32位二进制表示中1的个数。其中负数用补码表示。
 * 题目链接：
 * https://www.nowcoder.com/practice/8ee967e43c2c4ec193b040ea7fbb10b8?tpId=13&&tqId=11164&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking
 */
public class Jz11 {

    public static void main(String[] args) {
        System.out.println(numberOf1(10));
        System.out.println(numberOf2(10));
    }

    /**
     * n&(n-1)
     * 该位运算去除 n 的位级表示中最低的那一位。
     * n       : 10110100
     * n-1     : 10110011
     * n&(n-1) : 10110000
     *
     * @param n
     * @return
     */
    public static int numberOf1(int n) {
        int cnt = 0;
        while (n != 0) {
            cnt++;
            n &= n - 1;
        }
        return cnt;
    }

    /**
     * 库方法
     *
     * @param n
     * @return
     */
    public static int numberOf2(int n) {
        return Integer.bitCount(n);
    }
}

[Daily Message] Your smile is the most healing power, better than the most beautiful scenery in the world.