剑指Offer08 二进制中1的个数

/*************************************************************************
    > File Name: 08_NumOf1InBinary.c
    > Author: Juntaran
    > Mail: JuntaranMail@gmail.com
    > Created Time: 2016年08月29日 星期一 20时40分15秒
 ************************************************************************/

#include <stdio.h>
 
int NumberOf1_1(int n)
{
    int count = 0;
    int flag = 1;
    while (flag < n)
    {
        if (n & flag)
            count ++;
        flag = flag << 1;
    }
    return count;
}

int NumberOf1_2(int n)
{
    int count = 0;
    while (n)
    {
        ++ count;
        n = (n - 1) & n;
    }
    return count;
}

int main()
{
    int ret1 = 0;
    int ret2 = 0;
    
    int n = 5;
    ret1 = NumberOf1_1(n);
    ret2 = NumberOf1_2(n);
    printf("ret1 is %d
", ret1);
    printf("ret2 is %d
", ret2);
}