题解 | #判断两个IP是否属于同一子网#

#include <stdio.h>
int ipvaild(int ip[])
{
    for(int i = 0;i<4;i++)
    {
        if(ip[i]<0 || ip[i]>255)
        {
            return 0;
        }
    }
    return 1;
}

void otob(int ziwa,int a[])
{
    int index = 7;
    while(ziwa!=0)
    {
        a[index--] = ziwa%2;
        ziwa/=2;
    }
}
int ziwavaild(int ziwa[])
{
    int a[4][8] = {0};
    int flagz = 0;
    for(int i = 0;i<4;i++)
    {
        
        if(ziwa[i]<0 || ziwa[i]>255)
        {
            return 0;
        }

        otob(ziwa[i], a[i]);
    }

    for(int i = 0;i<4;i++)
    {
        for(int j = 0;j<8;j++)
        {
            if(a[i][j] == 0)
            {
                flagz = 1;
            }
            if(flagz)
            {
                if(a[i][j]==1)
                {
                    return 0;
                }
            }
        }
    }

    return 1;
}


int main() {
    int ziwa[4] = {0};
    int ip1[4] = {0},ip2[4] = {0};

    /*int a = 128;
    int l[8] = {0};
    otob(a, l);
    for(int i = 0;i<8;i++)
    {
        printf("%d",l[i]);
    }*/

    while (~scanf("%d.%d.%d.%d",&ziwa[0],&ziwa[1],&ziwa[2],&ziwa[3])) {
        scanf("%d.%d.%d.%d",&ip1[0],&ip1[1],&ip1[2],&ip1[3]);
        scanf("%d.%d.%d.%d",&ip2[0],&ip2[1],&ip2[2],&ip2[3]);
        //int res[8] = {0};
        
        if(ipvaild(ip1) && ipvaild(ip2) && ziwavaild(ziwa))
        {
            int flag = 1;
            for(int i = 0;i<4;i++)
            {
                if((ip1[i]&ziwa[i]) != (ip2[i]&ziwa[i]))
                {
                    flag = 0;
                    break;
                }
            }
            if(flag)
            {
                printf("0\n");
            }else {
                printf("2\n");
            }
        }else {
        printf("1\n");
        }
      
    
    }
    return 0;
}