HDU4712Hamming Distance随机化算法

Hamming Distance

Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 65535/65535 K (Java/Others) Total Submission(s): 736    Accepted Submission(s): 252

Problem Description

(From wikipedia) For binary strings a and b the Hamming distance is equal to the number of ones in a XOR b. For calculating Hamming distance between two strings a and b, they must have equal length. Now given N different binary strings, please calculate the minimum Hamming distance between every pair of strings.

 

Input

The first line of the input is an integer T, the number of test cases.(0<T<=20) Then T test case followed. The first line of each test case is an integer N (2<=N<=100000), the number of different binary strings. Then N lines followed, each of the next N line is a string consist of five characters. Each character is '0'-'9' or 'A'-'F', it represents the hexadecimal code of the binary string. For example, the hexadecimal code "12345" represents binary string "00010010001101000101".

 

Output

For each test case, output the minimum Hamming distance between every pair of strings.

 

Sample Input

2 2 12345 54321 4 12345 6789A BCDEF 0137F

 

Sample Output

6 7

 

Source

2013 ACM/ICPC Asia Regional Online —— Warmup

 

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#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <string>
#include <set>
#include <sstream>
#include <map>
#include <bitset>
#include <ctime>
using namespace std ;
#define zero {0}
#define INF 2000000000
#define eps 1e-6
typedef long long LL;
int cmp[16][16];
char data[1000005][6];
int fun(int q,int w)
{
    int a,b;
    int 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()
{
    #ifdef DeBUG
        freopen("C:\Users\Sky\Desktop\1.in","r",stdin);
    #endif
    for(int i=0;i<=15;i++)
    {
        for(int j=0;j<=15;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 n;
    int t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        for(int i=1;i<=n;i++)
            scanf("%s",data[i]);
        int ans=0x3f3f3f;
        srand((unsigned)time(NULL));
        for(int i=1;i<=300000;i++)
        {
            int a=rand()%n+1;
            int b=rand()%n+1;
            if(a==b)
                b=b%n+1;
            int tmp=fun(a,b);
            if(tmp<ans)
                ans=tmp;
        }
        cout<<ans<<endl;
    }
    
    return 0;
}