<p>On an <code>2 x 3</code> board, there are five tiles labeled from <code>1</code> to <code>5</code>, and an empty square represented by <code>0</code>. A <strong>move</strong> consists of choosing <code>0</code> and a 4-directionally adjacent number and swapping it.</p>

<p>The state of the board is solved if and only if the board is <code>[[1,2,3],[4,5,0]]</code>.</p>

<p>Given the puzzle board <code>board</code>, return <em>the least number of moves required so that the state of the board is solved</em>. If it is impossible for the state of the board to be solved, return <code>-1</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/slide1-grid.jpg" style="width: 244px; height: 165px;" />
<pre>
<strong>Input:</strong> board = [[1,2,3],[4,0,5]]
<strong>Output:</strong> 1
<strong>Explanation:</strong> Swap the 0 and the 5 in one move.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/slide2-grid.jpg" style="width: 244px; height: 165px;" />
<pre>
<strong>Input:</strong> board = [[1,2,3],[5,4,0]]
<strong>Output:</strong> -1
<strong>Explanation:</strong> No number of moves will make the board solved.
</pre>

<p><strong class="example">Example 3:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/slide3-grid.jpg" style="width: 244px; height: 165px;" />
<pre>
<strong>Input:</strong> board = [[4,1,2],[5,0,3]]
<strong>Output:</strong> 5
<strong>Explanation:</strong> 5 is the smallest number of moves that solves the board.
An example path:
After move 0: [[4,1,2],[5,0,3]]
After move 1: [[4,1,2],[0,5,3]]
After move 2: [[0,1,2],[4,5,3]]
After move 3: [[1,0,2],[4,5,3]]
After move 4: [[1,2,0],[4,5,3]]
After move 5: [[1,2,3],[4,5,0]]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>board.length == 2</code></li>
	<li><code>board[i].length == 3</code></li>
	<li><code>0 &lt;= board[i][j] &lt;= 5</code></li>
	<li>Each value <code>board[i][j]</code> is <strong>unique</strong>.</li>
</ul>

class Solution {
public:
    /*int slidingPuzzle(vector<vector<int>>& board) {
        string target = "123450", s = "";
        for (int i = 0; i < 2; i++){
            for (int j = 0; j < 3; j++){
                s += to_string(board[i][j]);
            }
        }
        vector<vector<int>> dirs{{1, 3}, {0, 2, 4}, {1, 5}, {0, 4}, {1, 3, 5}, {2, 4}};
        queue<string> q;
        q.push(s);
        int res = 0;
        unordered_set<string> visited;
        visited.insert(s);
        while(!q.empty()){
            for (int j = q.size(); j > 0; j--){
                string cur = q.front();
                q.pop();
                if (cur == target) return res;
                int ind = cur.find("0");
            //std::cout<<"cur = " << cur << std::endl;
           // std::cout<<"22" << std::endl;
           
          //  std::cout<<"ind = " << ind<< std::endl;
                for (int i = 0; i < dirs[ind].size(); i++){
              //  std::cout<<"33" << std::endl;
                    int dir = dirs[ind][i];
                    string tmp = cur;
                 //   std::cout<<"dir = " << dir<< std::endl;
                  //  std::cout<<" for cur = " << cur <<std::endl;
                    swap(tmp[ind], tmp[dir]);
                   // std::cout<<" after tmp = " << tmp <<std::endl;
                    if (visited.find(tmp) == visited.end()){
                        q.push(tmp);
                        visited.insert(tmp);
                    }
                }
            }
            res++;
        }
        return -1;
    }*/
    int slidingPuzzle(vector<vector<int>>& board) {
        vector<vector<int>> target{{1, 2, 3}, {4, 5, 0}};
        queue<pair<vector<vector<int>>, vector<int>>> q;
        for (int i = 0; i < 2; i++){
            for (int j = 0; j < 3; j++){
                if (board[i][j] == 0) q.push({board, {i, j}});
            }
        }
        vector<vector<int>> dirs{{0, -1}, {1, 0}, {-1, 0}, {0, 1}};
        int res = 0;
        //unordered_set<vector<vector<int>>> visited;
        set<vector<vector<int>>> visited;
        visited.insert(board);
        while(!q.empty()){
            for (int j = q.size(); j > 0; j--){
               // std::cout <<"j = "<< j << std::endl;
                auto cur = q.front();
                q.pop();
               
                if (cur.first == target) return res;
                int ind_x = cur.second[0];
                int ind_y = cur.second[1];
                for (int i = 0; i < 4; i++){
                 //   std::cout <<"1111  "<< std::endl;
                    int dir_x = dirs[i][0];
                    int dir_y = dirs[i][1];
                    int x = ind_x + dir_x;
                    int y = ind_y + dir_y;
                 //   std::cout <<"x = "  << x << std::endl;
                 //   std::cout <<"y = "  << y << std::endl;
                    if (x < 0 || x >= 2 || y < 0 || y >= 3){
                 //       std::cout <<"skip x = "  << x << std::endl;
                 //       std::cout <<" skip y = "  << y << std::endl;
                 //       std::cout <<"3333  "<< std::endl;
                        continue;
                    }
                 //   std::cout <<"2222  "<< std::endl;
                    vector<vector<int>> tmp = cur.first;
                    swap(tmp[ind_x][ind_y], tmp[x][y]);
                //    std::cout <<"new = "<< std::endl;
                    for (int k = 0; k < 2; k++){
                        for (int z = 0; z < 3; z++){
                            std::cout << tmp[k][z];
                        }
                //        std::cout << std::endl;
                    }
                    if (visited.find(tmp) == visited.end()){
                        q.push({tmp, {x, y}});
                        visited.insert(tmp);
                    }
                }
            }
            res++;
        }
        return -1;
    }

};
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