HDU 4712 Hamming Distance（随机算法）

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=4712

题目大意：任意两个数按位异或后二进制中含1的个数被称为海明距离，给定n个数，求出任意其中两个最小的海明数，输入是16进制。

Sample Input

2

2

12345

54321

4

12345

6789A

BCDEF

0137F

 

Sample Output

6

7

分析：用随机数来模拟，加srand()函数，放置产生伪随机数。代码有2个。

代码1：

# include<iostream>
# include<cstdio>
# include<cstring>
# include<ctime>
# include<cstdlib>
# define INF 0x3f3f3f3f

using namespace std;

int cmp[16][16];
char data[100005][6];

int solve(int q,int w)
{
    int a,b,ret=0;
    for(int i=0; i<5; i++)
    {
        char x = data[q][i];
        char y = data[w][i];
        if(x>='0' && x<='9')
            a = x-'0';
        else
            a = x-'A' + 10;
        if(y>='0' && y<='9')
            b = y-'0';
        else
            b = y-'A' + 10;
        ret += cmp[a][b];
    }
    return ret;
}
int main()
{
    int i,j;
    for(i=0; i<16; i++)
    {
        for(j=0; j<16; j++)
        {
            int ans=0;
            int tmp = i^j;
            for(int k=0; k<4; k++)
                if((1<<k) & tmp)
                    ans ++;
            cmp[i][j] = ans;
        }
    }

    int T,n;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d",&n);
        for(i=1; i<=n; i++)
            scanf("%s",data[i]);
        int ans = INF;
        srand((unsigned)time(NULL));
        for(i=1; i<=60000; i++)
        {
            int a = rand()%n + 1;
            int b = rand()%n + 1;
            if(a==b)
                b= b%n+1;
            int tmp = solve(a,b);
            if(tmp < ans)
                ans = tmp;
        }
        printf("%d
",ans);
    }
    return 0;
}

代码2：

# include<iostream>
# include<cstdio>
# include<cstring>
# include<ctime>
# include<cstdlib>
# define INF 0x3f3f3f3f

using namespace std;

int data[100005];

int get_one(int x)
{
    int ret = 0;
    while(x)
    {
        ret ++;
        x = x&(x-1);
    }
    return ret;
}
int main()
{
    srand((unsigned)time(NULL));
    int T,n,i;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d",&n);
        for(i=0; i<n; i++)
            scanf("%x",&data[i]);
        int ans = INF;
        for(i=100005; i>=0; i--)    //好奇怪，这里从前往后循环返回WA
        {
            int a = rand()%n ;
            int b = rand()%n ;
            if(a != b)
                ans = min(ans,get_one(data[a]^data[b]));
        }
        printf("%d
",ans);
    }
    return 0;
}