func_code_string: #include <bits/stdc++.h>   using namespace std;   int newMask[1000000][4];   bool canMove[1000000][4];   int mv[][2] = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};   int len;   int getMove(int x, int y) {     if (x == 1 && y == 0) return 0;     if (x == 0 && y == 1) return 1;     if (x == -1 && y == 0) return 2;     return 3;   }   vector<pair<int, int> > getLoc(int mask) {     vector<pair<int, int> > ret;     ret.push_back(make_pair(0, 0));     for (int i = 0; i + 1 < len; i++) {       int j = mask % 4;       mask /= 4;       int x = ret[ret.size() - 1].first + mv[j][0];       int y = ret[ret.size() - 1].second + mv[j][1];       ret.push_back(make_pair(x, y));     }     reverse(ret.begin(), ret.end());     return ret;   }   int getMask(vector<pair<int, int> > loc) {     int ret = 0;     for (int i = 0; i + 1 < loc.size(); i++) {       int x = loc[i].first - loc[i + 1].first;       int y = loc[i].second - loc[i + 1].second;       ret = ret * 4 + getMove(x, y);     }     return ret;   }   void precalc() {     int num = len - 1;     for (int i = 0; i < (1 << (2 * num)); i++) {       vector<pair<int, int> > loc = getLoc(i);       for (int x = 0; x < 4; x++) {         bool ok = 1;         for (int j = 1; j < loc.size(); j++) {           if (mv[x][0] == loc[j].first && mv[x][1] == loc[j].second) ok = 0;         }         if (ok) {           canMove[i][x] = true;           vector<pair<int, int> > newLoc = loc;           newLoc.erase(newLoc.begin());           newLoc.push_back(make_pair(mv[x][0], mv[x][1]));           newMask[i][x] = getMask(newLoc);         }       }     }   }   pair<int, int> l[10];   int n, m;   char a[100][100];   int dist[16][16][70000];   bool vis[16][16][70000];   int X, Y;   int ans;   int bfs(pair<int, int> v, int mask) {     ans = 1000000000;     queue<pair<int, int> > q1;     queue<int> q2;     q1.push(v);     q2.push(mask);     vis[v.first][v.second][mask] = 1;     while (!q1.empty()) {       v = q1.front();       q1.pop();       mask = q2.front();       q2.pop();       if (v == make_pair(X, Y)) ans = min(ans, dist[v.first][v.second][mask]);       for (int x = 0; x < 4; x++) {         if (!canMove[mask][x]) continue;         pair<int, int> u = v;         u.first += mv[x][0];         u.second += mv[x][1];         if (u.first < 0 || u.first >= n || u.second < 0 || u.second >= m ||             a[u.first][u.second] ==  # )           continue;         int uMask = newMask[mask][x];         if (vis[u.first][u.second][uMask]) continue;         dist[u.first][u.second][uMask] = 1 + dist[v.first][v.second][mask];         vis[u.first][u.second][uMask] = 1;         q1.push(u);         q2.push(uMask);       }     }     if (ans == 1000000000) return -1;     return ans;   }   void getInput() {     cin >> n >> m;     for (int i = 0; i < n; i++) {       for (int j = 0; j < m; j++) {         cin >> a[i][j];         if (a[i][j] >=  1  && a[i][j] <=  9 )           len++, l[a[i][j] -  0 ] = make_pair(i, j);         if (a[i][j] ==  @ ) X = i, Y = j;       }     }     vector<pair<int, int> > fLoc;     for (int i = len; i >= 1; i--) fLoc.push_back(l[i]);     precalc();     int mask = getMask(fLoc);     cout << bfs(fLoc[fLoc.size() - 1], mask) << endl;   }   int main() { getInput(); }   