C. Chessboard（ Educational Codeforces Round 41 (Rated for Div. 2)）

 //暴力

 #include <iostream>

 #include <algorithm>

 #include <string>

 using namespace std;

 const int N = ;

 string s1[N], s2[N], s3[N], s4[N];

 int a[N][N], b[N][N];

 int main()

 {

     int n;

     cin >> n;

     for (int i = ; i<n; i++)

         cin >> s1[i];

     cin.get();

     for (int i = ; i<n; i++)

         cin >> s2[i];

     cin.get();

     for (int i = ; i<n; i++)

         cin >> s3[i];

     cin.get();

     for (int i = ; i<n; i++)

         cin >> s4[i];

     for (int i = ; i<n; i++)

     for (int j = ; j < n; j++){

         //只有两种方式

         a[i][j] = (i + j) %  ==  ?  : ;

         b[i][j] = (i + j) %  ?  : ;

     }

     for (int i = ; i<n; i++)

     for (int j = ; j<n; j++)

         a[i][j] += , b[i][j] += ;

     //比较

     int ans = 1e9;

     int f = ;

     for (int i = ; i<n; i++)

     for (int j = ; j<n; j++)

         f += (s1[i][j] != a[i][j]) + (s2[i][j] != a[i][j]) + (s3[i][j] != b[i][j]) + (s4[i][j] != b[i][j]);

     ans = min(ans, f);

     f = ;

     for (int i = ; i<n; i++)

     for (int j = ; j<n; j++)

         f += (s1[i][j] != a[i][j]) + (s2[i][j] != b[i][j]) + (s3[i][j] != a[i][j]) + (s4[i][j] != b[i][j]);

     ans = min(ans, f);

     f = ;

     for (int i = ; i<n; i++)

     for (int j = ; j<n; j++)

         f += (s1[i][j] != a[i][j]) + (s2[i][j] != b[i][j]) + (s3[i][j] != b[i][j]) + (s4[i][j] != a[i][j]);

     ans = min(ans, f);

     f = ;

     for (int i = ; i<n; i++)

     for (int j = ; j<n; j++)

         f += (s1[i][j] != b[i][j]) + (s2[i][j] != a[i][j]) + (s3[i][j] != a[i][j]) + (s4[i][j] != b[i][j]);

     ans = min(ans, f);

     f = ;

     for (int i = ; i<n; i++)

     for (int j = ; j<n; j++)

         f += (s1[i][j] != b[i][j]) + (s2[i][j] != a[i][j]) + (s3[i][j] != b[i][j]) + (s4[i][j] != a[i][j]);

     ans = min(ans, f);

     f = ;

     for (int i = ; i<n; i++)

     for (int j = ; j<n; j++)

         f += (s1[i][j] != b[i][j]) + (s2[i][j] != b[i][j]) + (s3[i][j] != a[i][j]) + (s4[i][j] != a[i][j]);

     ans = min(ans, f);

     cout<< ans <<endl;

     system("pause");
     return ;

 }