劍指offer--面試題15：二進制中1的個數

#include <cstdio>

int NumberOf1_Solution1(int n)
{
    int count = 0;
    unsigned int flag = 1;
    while (flag)
    {
        if (n & flag)
            count++;

        flag = flag << 1;
    }

    return count;
}

int NumberOf1_Solution2(int n)
{
    int count = 0;

    while (n)
    {
        ++count;
        n = (n - 1) & n;
    }

    return count;
}

// ====================測試代碼====================


int main(int argc, char* argv[])
{
	int n;

	while(1)
	{
		printf("請輸入一個整數：");
		scanf("%d",&n);
		printf("方法1：%d表示的二進制中的1的個數為：%d\n",n,NumberOf1_Solution1(n));
		printf("方法2：%d表示的二進制中的1的個數為：%d\n",n,NumberOf1_Solution2(n));
	}
    return 0;
}

           

#include<stdio.h>

int count_1(int n)
{
	int count=0;
	while (n)
	{
		count++;
		n=n&(n-1);
	}
	return count;
}
int count_2(int n)
{
	if(n>0&&((n-1)&n)==0)
		return 1;
	else 
		return 0;
}

int main()
{
	int n,ret=0;
	while(1)
	{
		printf("請輸入一個整數:");
		scanf("%d", &n);
		ret = count_1(n);
		if (ret == 1)
			printf("方法1：%d是2的整數次方!\n",n);
		else
			printf("方法1：%d不是2的整數次方!\n",n);

		ret = count_2(n);
		if (ret == 1)
			printf("方法2：%d是2的整數次方!\n",n);
		else
			printf("方法2：%d不是2的整數次方!\n",n);
	}
	return 0;
}
           

#include<stdio.h>

int count(int m,int n)
{
	int t,count=0;
	t = m^n;
	while (t)
	{
		count++;
		t=t&(t-1);
	}
	return count;
}

int main()
{
	int num1,num2,ret=0;
	printf("請輸入兩個整數:");
	scanf("%d%d", &num1,&num2);
	ret = count(num1,num2);
	printf("改變%d的二進制表示中的%d位才能得到%d\n",num1,ret,num2);
	return 0;
}