计算长位数中的置位位数 [英] Count number of Set bits in a long number

问题描述

我需要计算长整数中设置位的数量.另外，我需要优化相同.我正在使用以下代码:

I need to count number of set bits in a long number. Also I need to optimize the same. I'm using the following code:

public static int countSetBits(long number) {
    int count = 0;
    while (number > 0) {
        ++count;
        number &= number - 1;
    }
    return count;
}

任何修改将不胜感激.

推荐答案

您可以按以下步骤编写而不加减法

You can write it without subtraction as follow

public static int countSetBits(long number) {
    int count = 0;
    while (number > 0) {
        count += number&1L;
        number>>=1L;
    }
    return count;
}

如果要使用Java的内置库，则可以使用

If You want to use Java's built-in libraries then can use bitCount

Long.bitCount(number)

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