[Link] https://www.acmicpc.net/problem/15683
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#include <algorithm>
#include <iostream>
#include <vector>
// #include <bits/stdc++.h>
using namespace std;
#define for0(i, n) for(int i = 0; i < n; i++)
#define for1(i, n) for(int i = 1; i <= n; i++)
#define fori(s, e) for(int i = s; i < e; i++)
typedef long long ll;
const int INF = 987654321;
int n, m, ans = INF;
int mm[8][8];
int di[4] = { -1, 0, 1, 0 };
int dj[4] = { 0, 1, 0, -1 };
bool inspect[8][8];
vector<int> cctv_vec;
vector<int> rot_vec;
// Long initialization code because of the auto-build parse error
vector<int> cctv_1 = {1};
vector<int> cctv_2 = {1, 3};
vector<int> cctv_3 = {0, 1};
vector<int> cctv_4 = {0, 1, 3};
vector<int> cctv_5 = {0, 1, 2, 3};
cctvs.push_back(cctv_1);
cctvs.push_back(cctv_2);
cctvs.push_back(cctv_3);
cctvs.push_back(cctv_4);
cctvs.push_back(cctv_5);
void inspect_dir(int ci, int cj, int dir) {
while(true) {
inspect[ci][cj] = true;
int ai = ci + di[dir], aj = cj + dj[dir];
if(ai < 0 || aj < 0 || ai >= n || aj >= m) break;
if(mm[ai][aj] == 6) break;
ci = ai, cj = aj;
}
}
void clear_inspect() {
for0(i, 8) for0(j, 8) inspect[i][j] = false;
}
void dfs(int nth) {
if(nth == cctv_vec.size()) {
clear_inspect();
int cctv_order = 0;
for0(i, n) {
for0(j, m) {
if(mm[i][j] == 0) continue;
else if(mm[i][j] == 6) {
inspect[i][j] = true;
continue;
}
int cctv = cctv_vec[cctv_order];
for(int ldir: cctvs[cctv - 1]) {
ldir += rot_vec[cctv_order];
if(ldir >= 4) ldir -= 4;
inspect_dir(i, j, ldir);
}
cctv_order++;
}
}
int non_inspect_cnt = 0;
for0(i, n) for0(j, m) if(inspect[i][j] == false) non_inspect_cnt++;
ans = min(ans, non_inspect_cnt);
return;
}
int examin_cnt;
switch(cctv_vec[nth]) {
case 5: examin_cnt = 1; break;
case 2: examin_cnt = 2; break;
default: examin_cnt = 4; break;
};
for(int i = 0; i < examin_cnt; i++) {
rot_vec[nth]+=i;
dfs(nth + 1);
rot_vec[nth]-=i;
}
}
void solve() {
rot_vec.resize(cctv_vec.size(), 0);
dfs(0);
}
int main() {
ios_base::sync_with_stdio(0);cin.tie(0); cout.tie(0);
cin >> n >> m;
int cctv_cnt = 0;
for0(i, n)
for0(j, m) {
cin >> mm[i][j];
if(mm[i][j] != 0 && mm[i][j] != 6) cctv_vec.push_back(mm[i][j]);
}
solve();
cout << ans;
return 0;
}