AtCoder ABC #099 D - Good Grid

abc099-d.cpp

#include <iostream>

using namespace std;

const int MAX_C = 30;
static int N, C;
static int D[MAX_C][MAX_C];
static int t[3][MAX_C];

int solve();

int solve() {
  int ans = 1 << 30;
  for (int i = 0; i < C; i++) {
    for (int j = 0; j < C; j++) {
      for (int k = 0; k < C; k++) {
        if (i != j && j != k && k != i) {
          int tt = 0;
          for (int l = 0; l < C; l++) {
            tt += D[l][i] * t[0][l];
            tt += D[l][j] * t[1][l];
            tt += D[l][k] * t[2][l];
          }
          ans = min(ans, tt);
        }
      }
    }
  }
  return ans;
}

int main() {
  cin >> N >> C;
  int x;
  for (int i = 0; i < C; i++) {
    for (int j = 0; j < C; j++) {
      cin >> x;
      D[i][j] = x;
    }
  }
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < N; j++) {
      cin >> x;
      t[(i + j) % 3][x - 1] += 1;
    }
  }
  cout << solve() << endl;
  return 0;
}