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Java 求矩阵中相邻数的最大面积_Java_Algorithm_Matrix_Depth First Search - Fatal编程技术网

Java 求矩阵中相邻数的最大面积

Java 求矩阵中相邻数的最大面积,java,algorithm,matrix,depth-first-search,Java,Algorithm,Matrix,Depth First Search,这不是家庭作业。我是一名编程初学者,这也是我在这里的第一篇帖子——请耐心听我说 我在这里找不到类似的问题 在一本初学者书中,我发现了以下问题: # Find the biggest area of adjacent numbers in this matrix: 1 3 2 2 2 4 3 3 3 2 4 4 4 3 1 2 3 3 #--> 13 times '3' 4 3 1 3 3 1 4 3 3 3 1 1 以下是我到目前为止使用的DFS实现的代码。到处都是“幻数”,方法是“公共

这不是家庭作业。我是一名编程初学者,这也是我在这里的第一篇帖子——请耐心听我说

我在这里找不到类似的问题

在一本初学者书中,我发现了以下问题:

# Find the biggest area of adjacent numbers in this matrix:
1 3 2 2 2 4
3 3 3 2 4 4
4 3 1 2 3 3 #--> 13 times '3'
4 3 1 3 3 1
4 3 3 3 1 1
以下是我到目前为止使用的DFS实现的代码。到处都是“幻数”,方法是“公共静态”等等-我打算在算法工作后修复这些东西

public class AdjacentAreaInMatrix {
    /*
     * Enums for the state of the Nodes, for use in DFS/BFS
     */
    private enum NodeState {
        Visited, InProgress, Unvisited
    }; 

    /*
     * These 2 'magic' numbers come from the hardcoded 'matrix' below,
     * cause it has 5 rows and 6 columns
     */
    public static final int ROWSCOUNT = 5;
    public static final int COLUMNSCOUNT = 6;

    /*
     * Two variables for counting the maximum sequence 
     * of numbers (as required by the problem definition)
     */
    private static int tempElementsCount = 0;
    private static int maxElementsCount = 1; // except if the matrix is empty, then it should be 0

    /*
     * The hardcoded matrix
     */
    private static final int[][] matrix = new int[][] { 
            { 1, 3, 2, 2, 2, 4 },
            { 3, 3, 3, 2, 4, 4 }, 
            { 4, 3, 1, 2, 3, 3 },
            { 4, 3, 1, 3, 3, 1 }, 
            { 4, 3, 3, 3, 1, 1 } };

    /* 
     * Create an auxiliary matrix 'state' to implement DFS. 
     * Initialize the whole matrix as 'unvisited' and
     * start DFS at the first element of the matrix
     */
    public static void DFS() {
        NodeState state[][] = new NodeState[ROWSCOUNT][COLUMNSCOUNT];
        // clear the state of the matrix
        for (int i = 0; i LT ROWSCOUNT; i++) {
            for (int j = 0; j LT COLUMNSCOUNT; j++) {
                state[i][j] = NodeState.Unvisited;
            }
        }
        runDFS(0, 0, state);    
    }

    /*
     * Using the auxiliary matrix "state[][]", use DFS to traverse the
     * 'real' matrix[][] 
     */
    public static void runDFS(int i, int j, NodeState state[][]) {
        state[i][j] = NodeState.InProgress;
        // traverse the whole matrix state[][] and recursively run runDFS() from the needed elements. 
        for (int rows = 0; rows LT ROWSCOUNT; rows++) {
            for (int columns = 0; columns LT COLUMNSCOUNT; columns++) {
                /*
                 * ----------------------------------------------------------------------
                 * For the logic in the 'if' statement regarding the adjacent elements:
                 * i0j0 i1j0 i1j0
                 * i0j1 i1j1 i2j1
                 * i0j2 i1j2 i2j2
                 * It uses the thing, that the sum of (i+j) for the coordinates of
                 * the elements above, below, on the left and on the right of i1j1
                 * are exactly +1/-1 of the sum of the coordinates of i1j1
                 * -> i1j2 to 1+2 = 3 
                 * -> i2j1 to 1+2 = 3 
                 * -> i1j1 to 1+1 = 2 (the current element) -> matrix[i][j] 
                 * -> i1j0 to 1+0 = 1 
                 * -> i0j1 to 1+0 = 1 
                 * ----------------------------------------------------------------------
                 */
                if ((matrix[i][j] == matrix[rows][columns]) // if the values are equal
                        && ((((i+j) - (rows + columns)) == 1) || (((i+j) - (rows + columns)) == -1))// and if the element is adjacent
                        && (state[rows][columns] == NodeState.Unvisited)) { // and if the element is still not visited
                    tempElementsCount++;
                    if (tempElementsCount > maxElementsCount) {
                        maxElementsCount = tempElementsCount;
                    }
                    runDFS(rows, columns, state); // recursively run DFS for each element, that "isEdge"
                } else {
                    // if the elements aren't [adjacent, equal and not visited], start the count again from '0'
                    tempElementsCount = 0;  
                }
            }
        }
        state[i][j] = NodeState.Visited;
    }

    public static void go() {
        AdjacentAreaInMatrix.DFS();
        System.out.println(maxElementsCount);
    }
}  

在调试了几天之后,每次调试都会使代码变得更加复杂…任何帮助都将不胜感激。提前谢谢。

我想问题是您每次都在重置tempElementsCount。想象一下,您的代码将如何在给定的矩阵上工作,您将看到,在runDFS()方法中,您总是使用if子句为false的元素(0,0)开始搜索,因此在可以使用其他(可能是相邻的)元素继续搜索之前,您重置了templementscont。希望我说得够清楚…

嗯。。。你的问题到底是什么?您需要算法方面的建议、特定bug方面的帮助或代码设计方面的意见吗?算法方面的建议会很好,谢谢。我非常清楚,代码设计不好(在算法工作之前我甚至都没有试着把它做好)。然而,上面显示的代码总是给我“1”,不管我从哪个矩阵开始它-我更喜欢在这里询问,而不是再次调试它。此外,在我找到的所有书籍/文章中,DFS/BFS的矩阵表示为1/0,表示有/没有边。我不确定我是否为这个矩阵使用了正确的数据表示(我以前没有写过DFS)。谢谢,你是对的。从(1,1)开始,不重置tempeleMetScont,得到12,这足够清楚,以便使算法工作正常。谢谢!对不起,我不能投票支持这个答案,因为我没有足够的声誉去做这件事。再次感谢你的帮助。