<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> </p> <p><strong>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>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>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> </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 <= board[i][j] <= 5</code></li> <li>Each value <code>board[i][j]</code> is <strong>unique</strong>.</li> </ul>