2015
09-17

# Hamming Distance

(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.

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".

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".

2
2
12345
54321
4
12345
6789A
BCDEF
0137F

6
7

#include<iostream>
#include<ctime>
#include<algorithm>
#include<cstdlib>
#include<cstdio>

using namespace std;

int a[100005];

int hamming(int x,int y)
{
x=x^y;
int count=0;
while(x)
{
x&=x-1;
count++;
}
return   count;
}

int min(int &a,int &b)
{
return  a<b?a:b;
}
int main()
{
int T;
cin>>T;

srand(time(0));
int n;
while(cin>>n)
{
for(int i=0;i<n;i++)
scanf("%x",&a[i]);
int  test=100000;
int x,y;
int ans=100;
while(test--)
{
x=rand()%n;
y=rand()%n;

while(x==y)
x=rand()%n;

ans=min(ans,hamming(a[x],a[y]));
}

cout<<ans<<endl;
}

}